add #to_ary to RepeatedField

MSVC protoc compiler fix

Support oneofs in MRI Ruby C extension.

<stdint.h> is not part of the standard, so I've added a workaround.

https://github.com/google/protobuf/issues/87

Fix illegal C++ use of reinterpret_cast<> to cast between nullptr_t and a pointer

- A golden-file test that ensures protoc produces known-valid output.
- A Ruby test that loads that golden file and ensures it actually works
  with the extension.

This split strategy allows us to test end-to-end without needing to
integrate the Ruby gem build system and the protoc build system. This is
desirable because we do not want a gem build/install to depend on
building protoc, and we do not want building protoc to depend on
building and testing the gem.

Support for maps in the MRI C Ruby extension.

Include names.h as java_names.h in the opensource tree

This adds the Map container and support for parsing and serializing maps
in the protobuf wire format (as defined by the C++ implementation, with
MapEntry submessages in a repeated field). JSON map
serialization/parsing are not yet supported as these will require some
changes to upb as well.

Update python version / setuptools instructions

 Add __version__

Improved little endian byte order detection

Reflect the change that protobuf should now only be supporting 2.6+ (I'd guess note python 3.x+ when its supported in implementation)

Refer to the Python Packaging User Guide for installing setuptools (and pip) instead of out of date telecommunity guide.

Including <sys/param.h> on Mac/iOS doesn't define __BYTE_ORDER so
PROTOBUF_LITTLE_ENDIAN was never being defined. This commit adds a check
for the __LITTLE_ENDIAN__ macro which is defined by clang and Apple gcc on
little endian architectures.

Support Ruby code generation only for proto3.