Move all Firestore Objective-C to Objective-C++ (#734)

* Move all Firestore files to Objective-C++
* Update project file references
* Don't use module imports from Objective-C++
* Use extern "C" for C-accessible globals
* Work around more stringent type checking in Objective-C++
  * NSMutableDictionary ivars aren't implicitly casted to NSDictionary
  * FSTMaybeDocument callback can't be passed a function that accepts
    FSTDocument
  * NSComparisonResult can't be multiplied by -1 without casting
* Add a #include <inttypes.h> where needed
* Avoid using C++ keywords as variables
* Remove #if __cplusplus guards

10 files changed, 6 insertions, 6 deletions

diff --git a/Firestore/Example/Tests/API/FIRCollectionReferenceTests.m b/Firestore/Example/Tests/API/FIRCollectionReferenceTests.mm
index 547078f..547078f 100644
--- a/Firestore/Example/Tests/API/FIRCollectionReferenceTests.m
+++ b/Firestore/Example/Tests/API/FIRCollectionReferenceTests.mm
diff --git a/Firestore/Example/Tests/API/FIRDocumentReferenceTests.m b/Firestore/Example/Tests/API/FIRDocumentReferenceTests.mm
index cc2b431..cc2b431 100644
--- a/Firestore/Example/Tests/API/FIRDocumentReferenceTests.m
+++ b/Firestore/Example/Tests/API/FIRDocumentReferenceTests.mm
diff --git a/Firestore/Example/Tests/API/FIRDocumentSnapshotTests.m b/Firestore/Example/Tests/API/FIRDocumentSnapshotTests.mm
index 677d385..677d385 100644
--- a/Firestore/Example/Tests/API/FIRDocumentSnapshotTests.m
+++ b/Firestore/Example/Tests/API/FIRDocumentSnapshotTests.mm
diff --git a/Firestore/Example/Tests/API/FIRFieldPathTests.m b/Firestore/Example/Tests/API/FIRFieldPathTests.mm
index 679ea89..679ea89 100644
--- a/Firestore/Example/Tests/API/FIRFieldPathTests.m
+++ b/Firestore/Example/Tests/API/FIRFieldPathTests.mm
diff --git a/Firestore/Example/Tests/API/FIRFieldValueTests.m b/Firestore/Example/Tests/API/FIRFieldValueTests.mm
index becf7d6..575dfee 100644
--- a/Firestore/Example/Tests/API/FIRFieldValueTests.m
+++ b/Firestore/Example/Tests/API/FIRFieldValueTests.mm
@@ -26,19 +26,19 @@ NS_ASSUME_NONNULL_BEGIN
 @implementation FIRFieldValueTests
 
 - (void)testEquals {
-  FIRFieldValue *delete = [FIRFieldValue fieldValueForDelete];
+  FIRFieldValue *deleted = [FIRFieldValue fieldValueForDelete];
   FIRFieldValue *deleteDup = [FIRFieldValue fieldValueForDelete];
   FIRFieldValue *serverTimestamp = [FIRFieldValue fieldValueForServerTimestamp];
   FIRFieldValue *serverTimestampDup = [FIRFieldValue fieldValueForServerTimestamp];
-  XCTAssertEqualObjects(delete, deleteDup);
-  XCTAssertNotEqualObjects(delete, nil);
+  XCTAssertEqualObjects(deleted, deleteDup);
+  XCTAssertNotEqualObjects(deleted, nil);
   XCTAssertEqualObjects(serverTimestamp, serverTimestampDup);
   XCTAssertNotEqualObjects(serverTimestamp, nil);
-  XCTAssertNotEqualObjects(delete, serverTimestamp);
+  XCTAssertNotEqualObjects(deleted, serverTimestamp);
 
-  XCTAssertEqual([delete hash], [deleteDup hash]);
+  XCTAssertEqual([deleted hash], [deleteDup hash]);
   XCTAssertEqual([serverTimestamp hash], [serverTimestamp hash]);
-  XCTAssertNotEqual([delete hash], [serverTimestamp hash]);
+  XCTAssertNotEqual([deleted hash], [serverTimestamp hash]);
 }
 
 @end
diff --git a/Firestore/Example/Tests/API/FIRGeoPointTests.m b/Firestore/Example/Tests/API/FIRGeoPointTests.mm
index 4de80a8..4de80a8 100644
--- a/Firestore/Example/Tests/API/FIRGeoPointTests.m
+++ b/Firestore/Example/Tests/API/FIRGeoPointTests.mm
diff --git a/Firestore/Example/Tests/API/FIRQuerySnapshotTests.m b/Firestore/Example/Tests/API/FIRQuerySnapshotTests.mm
index 067425a..067425a 100644
--- a/Firestore/Example/Tests/API/FIRQuerySnapshotTests.m
+++ b/Firestore/Example/Tests/API/FIRQuerySnapshotTests.mm
diff --git a/Firestore/Example/Tests/API/FIRQueryTests.m b/Firestore/Example/Tests/API/FIRQueryTests.mm
index 83f90be..83f90be 100644
--- a/Firestore/Example/Tests/API/FIRQueryTests.m
+++ b/Firestore/Example/Tests/API/FIRQueryTests.mm
diff --git a/Firestore/Example/Tests/API/FIRSnapshotMetadataTests.m b/Firestore/Example/Tests/API/FIRSnapshotMetadataTests.mm
index a4d321b..a4d321b 100644
--- a/Firestore/Example/Tests/API/FIRSnapshotMetadataTests.m
+++ b/Firestore/Example/Tests/API/FIRSnapshotMetadataTests.mm
diff --git a/Firestore/Example/Tests/API/FSTAPIHelpers.m b/Firestore/Example/Tests/API/FSTAPIHelpers.mm
index da899b7..da899b7 100644
--- a/Firestore/Example/Tests/API/FSTAPIHelpers.m
+++ b/Firestore/Example/Tests/API/FSTAPIHelpers.mm