[java/cs] Unit tests-related fixes:
- Fixed classes implementing partially-applied interfaces
- Rewritten overload handling, and fixed most issues regarding overloads ambiguity
- Fixed override-related problems, coming from Codegen.fix_overrides


git-svn-id: http://haxe.googlecode.com/svn/trunk@6485 f16182fa-f095-11de-8f43-4547254af6c6