1) Remove CSharpOptions
2) A new version of DescriptorProtoFile (with manual changes from codegen - it would otherwise be Descriptor.cs)
3) Turn off CLS compliance (which we'll remove from the codebase entirely; I don't think it's actually relevant these days)
4) Add "public imports" to FileDescriptor, with code broadly copied from the Java codebase.
Lots more changes to commit before it will build and tests run, but one step at a time...

Add C# generator files to the VS project for libprotoc

Also ignore Windows native build output files.

C# protocol buffers (initial pull request)

Rewrite of C# protogen to C++ (initial version)

Pulling protobuf-csharp-port into csharp/ directory

This is necessary for testing on iOS.

Change-Id: I54ec1e3aa2e9fbfff9a6cd6580920a6a62069b63

Fix for issue 283: JSON handler cleanup typo causing segfault.

Includes repro test case from @wfarr.

Migrate Python tests to stdlib unittest, drop apputils dependency.

Use stdlib's 'unittest' instead.

We already run all tests with and without `--cpp_implementation`

Added Python to Travis build and clarified setup instructions.