Change lookahead_list into a queue

Using builtin `commandline -f`, one would expect to have commands executed in
the order that they were given.  This motivates the change to a queue.

Unfortunately, fish internals still need lookahead_list to act as a stack.  Add
and rename functions to support both cases and have lookahead_list as
a std::deque internally.

This code is delicate, and we should probably dog-food this in nightly for
a while before the next-minor release.

Fixes #1567

1 files changed, 2 insertions, 2 deletions

diff --git a/input.h b/input.h
index 9864d730..a3a3a076 100644
--- a/input.h
+++ b/input.h
@@ -112,11 +112,11 @@ void input_destroy();
 wint_t input_readch(bool allow_commands = true);
 
 /**
-   Push a character or a readline function onto the stack of unread
+   Enqueue a character or a readline function to the queue of unread
    characters that input_readch will return before actually reading from fd
    0.
  */
-void input_unreadch(wint_t ch);
+void input_queue_ch(wint_t ch);
 
 
 /**