Merge new string builtin

This adds the new builtin 'string' which supports various string
manipulation and matching algorithms, including PCRE based regular
expressions.

Fixes #2296

Squashed commit of the following:

commit 4c3eaeb6e57d76463e9683c327142b0aeafb92b8
Author: ridiculousfish <corydoras@ridiculousfish.com>
Date:   Sat Sep 12 12:51:30 2015 -0700

    Remove testdata and doc dirs from pcre2 source

commit b2a8b4b50f2398b204fb72cfe4b5ba77ece2e1ab
Merge: 11c8a47 7974aab
Author: ridiculousfish <corydoras@ridiculousfish.com>
Date:   Sat Sep 12 12:32:40 2015 -0700

    Merge branch 'string' of git://github.com/msteed/fish-shell into string-test

commit 7974aab6d367f999f1140ab34c2535cef5cf3b00
Author: Michael Steed <msteed@saltstack.com>
Date:   Fri Sep 11 13:00:02 2015 -0600

    build pcre2 lib only, no docs

commit eb20b43d2d96b7e6d24618158ce71078de83c40b
Merge: 1a09e70 5f519cb
Author: Michael Steed <msteed68@gmail.com>
Date:   Thu Sep 10 20:00:47 2015 -0600

    Merge branch 'string' of github.com:msteed/fish-shell into string

commit 1a09e709d028393c9e9e6dc9a84278f399a15f3d
Author: Michael Steed <msteed68@gmail.com>
Date:   Thu Sep 10 19:58:24 2015 -0600

    rebase on master & address the fallout

commit a0ec9772cd1a0a548a501a7633be05dab4e5ee46
Author: Michael Steed <msteed68@gmail.com>
Date:   Thu Sep 10 19:26:45 2015 -0600

    use fish's wildcard_match() for glob matching

commit 64c25a01e3f7234f220ba13545cf658a7492b1a4
Author: Michael Steed <msteed68@gmail.com>
Date:   Thu Aug 27 08:19:23 2015 -0600

    some fixes from review

    - string_get_arg_stdin(): simplify and don't discard the argument when
      the trailing newline is absent
    - fix calls to pcre2 for e.g. string match -r -a 'a*' 'b'
    - correct test for args coming from stdin

commit ece7f35ec5f4093763627d68d671b6c0c876896d
Author: Michael Steed <msteed68@gmail.com>
Date:   Sat Aug 22 19:35:56 2015 -0600

    fixes from review

    - Makefile.in: restore iwyu target
    - regex_replacer_t::replace_matches(): correct size passed to realloc()

commit 9ff7477a926c4572e26171cab3cd42f8086be678
Author: Michael Steed <msteed68@gmail.com>
Date:   Thu Aug 20 13:08:33 2015 -0600

    Minor doc improvements

commit baf4e096b22dde3063b85b833795eb570d660ba7
Author: Michael Steed <msteed68@gmail.com>
Date:   Wed Aug 19 18:29:02 2015 -0600

    another attempt to fix the ci build

commit 896a2c2b279a419747bea26102229fbe84534a6f
Author: Michael Steed <msteed68@gmail.com>
Date:   Wed Aug 19 18:03:49 2015 -0600

    Updates after review comments

    - make match/replace without -a operate on the first match on each
      argument
    - use different exit codes for "no operation performed" and errors, as
      grep does
    - refactor regex compile code
    - use human-friendly error messages from pcre2
    - improve error handling & reporting elsewhere
    - add a few tests
    - make some doc fixes
    - some simplification & cleanup
    - fix ci build failure (I hope)

commit efd47dcbda2ca247d58bee56a7774cd75a1062fd
Author: Michael Steed <msteed68@gmail.com>
Date:   Wed Aug 12 00:26:07 2015 -0600

    fix dependencies for parallel make

commit ed0850e2db467362066a3d94e3ececd17c1756cd
Author: Michael Steed <msteed68@gmail.com>
Date:   Tue Aug 11 23:37:22 2015 -0600

    Add missing pcre2 files + .gitignore

commit 9492e7a7e929c03554336be1ddf80ca6b37f53c5
Author: Michael Steed <msteed68@gmail.com>
Date:   Tue Aug 11 22:44:05 2015 -0600

    add pcre2-10.20 and update license.hdr

commit 1a60b933718feb20c0bf7c9e257b8e495014ea1b
Author: Michael Steed <msteed68@gmail.com>
Date:   Tue Aug 11 22:41:19 2015 -0600

    add string builtin files

    - string builtin source, tests, & docs
    - changes to configure.ac & Makefile.in

commit 5f519cb2a2c05213e0a88a7add7af288bc1c1352
Author: Michael Steed <msteed68@gmail.com>
Date:   Thu Sep 10 19:26:45 2015 -0600

    use fish's wildcard_match() for glob matching

commit 2ecd24f79500879e2de5bdf1b4c19dd44fc6ac85
Author: Michael Steed <msteed68@gmail.com>
Date:   Thu Aug 27 08:19:23 2015 -0600

    some fixes from review

    - string_get_arg_stdin(): simplify and don't discard the argument when
      the trailing newline is absent
    - fix calls to pcre2 for e.g. string match -r -a 'a*' 'b'
    - correct test for args coming from stdin

commit 45b777e4dc85c05cd4a186f4bdcae543c21aaf08
Author: Michael Steed <msteed68@gmail.com>
Date:   Sat Aug 22 19:35:56 2015 -0600

    fixes from review

    - Makefile.in: restore iwyu target
    - regex_replacer_t::replace_matches(): correct size passed to realloc()

commit 981cbb6ddf742a5fe8881af916e7b870b7e6422a
Author: Michael Steed <msteed68@gmail.com>
Date:   Thu Aug 20 13:08:33 2015 -0600

    Minor doc improvements

commit ddb6a2a8fdb6aa31aad41e80d5481bb32c6ed8ff
Author: Michael Steed <msteed68@gmail.com>
Date:   Wed Aug 19 18:29:02 2015 -0600

    another attempt to fix the ci build

commit 1e34e3191b028162863d263e9868052f75194aa5
Author: Michael Steed <msteed68@gmail.com>
Date:   Wed Aug 19 18:03:49 2015 -0600

    Updates after review comments

    - make match/replace without -a operate on the first match on each
      argument
    - use different exit codes for "no operation performed" and errors, as
      grep does
    - refactor regex compile code
    - use human-friendly error messages from pcre2
    - improve error handling & reporting elsewhere
    - add a few tests
    - make some doc fixes
    - some simplification & cleanup
    - fix ci build failure (I hope)

commit 34232e152df17a3cfbf0a094dd51d148a4f04e6f
Author: Michael Steed <msteed68@gmail.com>
Date:   Wed Aug 12 00:26:07 2015 -0600

    fix dependencies for parallel make

commit 00d7e781697f53454beb91c1d0fc4b2d28d6e034
Author: Michael Steed <msteed68@gmail.com>
Date:   Tue Aug 11 23:37:22 2015 -0600

    Add missing pcre2 files + .gitignore

commit 4498aa5f576e09634f7f619443e74d2f33c108e4
Author: Michael Steed <msteed68@gmail.com>
Date:   Tue Aug 11 22:44:05 2015 -0600

    add pcre2-10.20 and update license.hdr

commit 290c58c72e22db644ccf6fa9088051644980ed0a
Author: Michael Steed <msteed68@gmail.com>
Date:   Tue Aug 11 22:41:19 2015 -0600

    add string builtin files

    - string builtin source, tests, & docs
    - changes to configure.ac & Makefile.in

1 files changed, 41 insertions, 20 deletions

diff --git a/Makefile.in b/Makefile.in
index 45f922d6..a759460a 100644
--- a/Makefile.in
+++ b/Makefile.in
@@ -50,14 +50,28 @@ docdir = @docdir@
 localedir = @localedir@
 
 #
+# pcre2
+#
+
+PCRE2_WIDTH = @WCHAR_T_BITS@
+PCRE2_DIR = pcre2-10.20
+PCRE2_CXXFLAGS = -I$(PCRE2_DIR)/src
+PCRE2_LIBDIR = $(PCRE2_DIR)/.libs
+PCRE2_LIB = $(PCRE2_LIBDIR)/libpcre2-$(PCRE2_WIDTH).a
+PCRE2_H = $(PCRE2_DIR)/src/pcre2.h
+PCRE2_CONFIG = --disable-pcre2-8 --enable-pcre2-$(PCRE2_WIDTH) --disable-shared
+
+#
 # Various flags
 #
 
 MACROS = -DLOCALEDIR=\"$(localedir)\" -DPREFIX=L\"$(prefix)\" -DDATADIR=L\"$(datadir)\" -DSYSCONFDIR=L\"$(sysconfdir)\" -DBINDIR=L\"$(bindir)\" -DDOCDIR=L\"$(docdir)\"
-CXXFLAGS = @CXXFLAGS@ -iquote. -iquote./src/ $(MACROS) $(EXTRA_CXXFLAGS)
+CXXFLAGS = @CXXFLAGS@ -iquote. -iquote./src/ $(MACROS) $(PCRE2_CXXFLAGS) $(EXTRA_CXXFLAGS)
 CPPFLAGS = @CPPFLAGS@
 LDFLAGS = @LDFLAGS@
-LIBS = @LIBS@
+PCRE2 = pcre2-10.20
+LIBS_PCRE2 = -L$(PCRE2_LIBDIR) -lpcre2-$(PCRE2_WIDTH)
+LIBS = @LIBS@ $(LIBS_PCRE2)
 LDFLAGS_FISH = ${LDFLAGS} @LDFLAGS_FISH@
 
 #
@@ -96,7 +110,7 @@ FISH_INDENT_OBJS := obj/fish_indent.o obj/print_help.o $(FISH_OBJS)
 BUILTIN_FILES := src/builtin_set.cpp src/builtin_commandline.cpp	\
 	src/builtin_ulimit.cpp src/builtin_complete.cpp	\
 	src/builtin_jobs.cpp src/builtin_set_color.cpp	\
-	src/builtin_printf.cpp
+	src/builtin_printf.cpp src/builtin_string.cpp
 
 
 #
@@ -474,6 +488,8 @@ messages.pot: src/*.cpp src/*.h share/completions/*.fish share/functions/*.fish
 
 builtin.o: $(BUILTIN_FILES)
 
+src/builtin_string.cpp: $(PCRE2_H)
+
 
 #
 # Generate the internal help functions by making doxygen create
@@ -778,15 +794,19 @@ obj:
 # Build the fish program.
 #
 
-fish: $(FISH_OBJS) obj/fish.o
+fish: $(FISH_OBJS) obj/fish.o $(PCRE2_LIB)
 	$(CXX) $(CXXFLAGS) $(LDFLAGS_FISH) $(FISH_OBJS) obj/fish.o $(LIBS) -o $@
 
+$(PCRE2_H):
+	(cd $(PCRE2_DIR) && autoreconf -i && ./configure $(PCRE2_CONFIG) && make libpcre2-$(PCRE2_WIDTH).la)
+
+$(PCRE2_LIB): $(PCRE2_H)
 
 #
 # Build the fish_tests program.
 #
 
-fish_tests: $(FISH_TESTS_OBJS)
+fish_tests: $(FISH_TESTS_OBJS) $(PCRE2_LIB)
 	$(CXX) $(CXXFLAGS) $(LDFLAGS_FISH) $(FISH_TESTS_OBJS) $(LIBS) -o $@
 
 
@@ -794,7 +814,7 @@ fish_tests: $(FISH_TESTS_OBJS)
 # Build the fish_indent program.
 #
 
-fish_indent: $(FISH_INDENT_OBJS)
+fish_indent: $(FISH_INDENT_OBJS) $(PCRE2_LIB)
 	$(CXX) $(CXXFLAGS) $(LDFLAGS) $(FISH_INDENT_OBJS) $(LIBS) -o $@
 
 
@@ -889,6 +909,7 @@ obj/builtin.o: src/wcstringutil.h src/builtin_set.cpp src/util.h
 obj/builtin.o: src/builtin_commandline.cpp src/builtin_complete.cpp
 obj/builtin.o: src/builtin_ulimit.cpp src/builtin_jobs.cpp
 obj/builtin.o: src/builtin_set_color.cpp src/output.h src/builtin_printf.cpp
+obj/builtin.o: src/builtin_string.cpp
 obj/builtin_test.o: config.h src/common.h src/fallback.h src/signal.h
 obj/builtin_test.o: src/builtin.h src/io.h src/wutil.h src/proc.h
 obj/builtin_test.o: src/parse_tree.h src/tokenizer.h src/parse_constants.h
@@ -944,8 +965,8 @@ obj/fish_tests.o: src/builtin.h src/function.h src/event.h src/autoload.h
 obj/fish_tests.o: src/lru.h src/wutil.h src/expand.h src/parser.h
 obj/fish_tests.o: src/output.h src/exec.h src/path.h src/history.h
 obj/fish_tests.o: src/iothread.h src/postfork.h src/parse_util.h src/pager.h
-obj/fish_tests.o: src/screen.h src/input.h src/input_common.h src/utf8.h
-obj/fish_tests.o: src/env_universal_common.h src/wcstringutil.h
+obj/fish_tests.o: src/screen.h src/input.h src/input_common.h src/wildcard.h
+obj/fish_tests.o: src/utf8.h src/env_universal_common.h src/wcstringutil.h
 obj/fish_version.o: src/fish_version.h
 obj/function.o: config.h src/wutil.h src/common.h src/fallback.h src/signal.h
 obj/function.o: src/autoload.h src/lru.h src/function.h src/event.h src/env.h
@@ -963,15 +984,15 @@ obj/history.o: src/io.h src/common.h src/complete.h src/highlight.h src/env.h
 obj/history.o: src/color.h src/parse_constants.h src/parse_tree.h
 obj/history.o: src/tokenizer.h src/wutil.h src/history.h src/path.h
 obj/history.o: src/iothread.h src/lru.h
+obj/input_common.o: config.h src/fallback.h src/signal.h src/util.h
+obj/input_common.o: src/common.h src/input_common.h
+obj/input_common.o: src/env_universal_common.h src/wutil.h src/env.h
+obj/input_common.o: src/iothread.h
 obj/input.o: config.h src/fallback.h src/signal.h src/wutil.h src/common.h
 obj/input.o: src/reader.h src/io.h src/complete.h src/highlight.h src/env.h
 obj/input.o: src/color.h src/parse_constants.h src/proc.h src/parse_tree.h
 obj/input.o: src/tokenizer.h src/input_common.h src/input.h src/parser.h
 obj/input.o: src/event.h src/output.h
-obj/input_common.o: config.h src/fallback.h src/signal.h src/util.h
-obj/input_common.o: src/common.h src/input_common.h
-obj/input_common.o: src/env_universal_common.h src/wutil.h src/env.h
-obj/input_common.o: src/iothread.h
 obj/intern.o: config.h src/fallback.h src/signal.h src/common.h src/intern.h
 obj/io.o: config.h src/fallback.h src/signal.h src/wutil.h src/common.h
 obj/io.o: src/exec.h src/io.h
@@ -998,14 +1019,6 @@ obj/parse_execution.o: src/builtin.h src/exec.h
 obj/parse_productions.o: src/parse_productions.h src/common.h config.h
 obj/parse_productions.o: src/fallback.h src/signal.h src/parse_constants.h
 obj/parse_productions.o: src/parse_tree.h src/tokenizer.h
-obj/parse_tree.o: src/common.h config.h src/fallback.h src/signal.h
-obj/parse_tree.o: src/parse_constants.h src/parse_productions.h
-obj/parse_tree.o: src/parse_tree.h src/tokenizer.h src/wutil.h src/proc.h
-obj/parse_tree.o: src/io.h
-obj/parse_util.o: config.h src/fallback.h src/signal.h src/util.h src/wutil.h
-obj/parse_util.o: src/common.h src/tokenizer.h src/parse_util.h
-obj/parse_util.o: src/parse_constants.h src/expand.h src/env.h src/wildcard.h
-obj/parse_util.o: src/complete.h src/parse_tree.h src/builtin.h src/io.h
 obj/parser.o: config.h src/fallback.h src/signal.h src/common.h src/wutil.h
 obj/parser.o: src/proc.h src/io.h src/parse_tree.h src/tokenizer.h
 obj/parser.o: src/parse_constants.h src/parser.h src/event.h src/function.h
@@ -1014,6 +1027,14 @@ obj/parser.o: src/highlight.h src/color.h src/sanity.h src/intern.h
 obj/parser.o: src/parse_util.h src/parse_execution.h
 obj/parser_keywords.o: config.h src/fallback.h src/signal.h src/common.h
 obj/parser_keywords.o: src/parser_keywords.h
+obj/parse_tree.o: src/common.h config.h src/fallback.h src/signal.h
+obj/parse_tree.o: src/parse_constants.h src/parse_productions.h
+obj/parse_tree.o: src/parse_tree.h src/tokenizer.h src/wutil.h src/proc.h
+obj/parse_tree.o: src/io.h
+obj/parse_util.o: config.h src/fallback.h src/signal.h src/util.h src/wutil.h
+obj/parse_util.o: src/common.h src/tokenizer.h src/parse_util.h
+obj/parse_util.o: src/parse_constants.h src/expand.h src/env.h src/wildcard.h
+obj/parse_util.o: src/complete.h src/parse_tree.h src/builtin.h src/io.h
 obj/path.o: config.h src/fallback.h src/signal.h src/common.h src/env.h
 obj/path.o: src/wutil.h src/path.h src/expand.h src/parse_constants.h
 obj/postfork.o: src/signal.h src/common.h config.h src/fallback.h src/proc.h