JSON parsing & text generation is now enum-identifier aware.

When Parsing JSON, it will read enums either as int values, identifiers
specific to the enum type, or strings containing those identifiers.

When generating text, it will output enum identifiers by default
(this can be turned off in favor of integers, like before).

Change-Id: If28b0a1f8f27de79aff3e626f40c0c0b271c325a
Tested: on Windows and Linux
Bug: 16214968
Port FlatBuffers to Go.

Implement code generation and runtime library for Go, derived from the
Java implementation. Additionally, the test suite verifies:

 - the exact bytes in the Builder buffer during object construction,
 - vtable deduplication, and
 - table construction, via a fuzzer derived from the C++ implementation.

Change-Id: Ib95a019c684891def2b50281e570b4843fea7baa
Small fixes to the core C++ FlatBuffers implementation.

- Ensured weak linkage with the version string is not used on Windows,
  especially cygwin (which throws a linker error).
- Avoided a VS debug error for taking the address of the first element
  of an empty vector.
- Made copy/assignment constructors for downward_vector and
  FlatBufferBuilder private, to avoid people unintentionally making
  expensive copies.
- Using the more correct _WIN32 instead of WIN32

Change-Id: I801b5c8b159e3721af6d1ef0978a3247ba168bab
Tested: on Windows (VS + Cygwin) and Linux.
A feature that officially supports nested FlatBuffers.

Generates convenient accessors for the nested root.

Change-Id: Ic0b1531de7ace475ff2a7b1f430d27f41c838430
Tested: on Windows.
Made sure tests.cpp is testing the new vector iterator functionality.

Also fixes a potential big-endian bug, and makes iterators work
correctly with pointer types.

Change-Id: Ib7f88fe9e6053d1a9afa7895fba0695627c158b1
Tested: on Windows and Linux
Added a `bit_flags` attribute to enum declarations that 1<<N every value.

Change-Id: Ib9ec0cb3ddec60b1ca124eaf815fb1ae0cc53e1c
Tested: on Windows and Linux
Bug: 16186562
Updated benchmark chart with stats for pugixml.

Change-Id: I23d7db5b62ca52fee49e1bedcf7d7d8d74957cf8
Tested: on Windows.