Fix off by one in FileReadStream::Peek4()

Optimize FileReadStream and BasicIStreamWrapper.

GenericRegex: don't throw/abort on syntax error (unclosed parenthesis).

Until Read() reaches EOF, Peek4() must not take off by one in
bufferLast_ into account; otherwise a buffer of size exactly 4 always
returns NULL.

On (my) linux, perftest reports:
- ~40% gain for FileReadStream (Take() loop),
- ~10% gain for ReaderParse_DummyHandler_FileReadStream.

With the same logic applied to BasicIStreamWrapper, which thus can now
also be created with a user buffer, performances align with those of
FileReadStream (same buffer size).

The "unbuffered" versions (added for FileReadStream) work solely with
the internal peekBuffer (Ch[4]) and are measured in perftest.  When
performances don't matter much, they can avoid the use of large
stack/heap buffers.

Fix a memory leak for invalid std::regex in Schema.

Use passed in allocator for internal regex parser.

silence clang-7 self-assign-overloaded warning

Fix warning when NDEBUG is defined [-Wunused-variable]

Because `isPeek()` is side effect free this should not change anything.

The reason this warning is not shown in the unit tests is because the asserts
are always evaluated in the unit test:

#define RAPIDJSON_ASSERT(x) (!(x) ? throw AssertException(RAPIDJSON_STRINGIFY(x)) : (void)0u)

Co-Authored-By: yhager <yhager@users.noreply.github.com>

Add test case on kParseNumbersAsStringsFlag being able to load big ints

See issue #1368.

fix tutorial error

faq: fix document insertion example

GenericDocument contructor requires a pointer to an Allocator, but GetAllocator() only
returns a reference.
Signed-off-by: Julien Courtat <julien.courtat@aqsacom.com>

Add RAPIDJSON_NOEXCEPT_ASSERT

Update appveyor rule to support VS2017.

Fix the compiling problems in VS

Guard against min/max being macros in reader.h

Handle non-throwing exception specifications that can still throw #1280

Wrap all WriteXxx() calls within EndValue()

This attempts to fix issue #1336.

Fix SIGBUS due to unaligned access

Fixed parentheses in reader.h which were required to prevent the using of max macro