Csharp wrapper

The csharp wrapper now works on Linux/Mono.

1. Switched cmake csharp/mono module toolkit
2. Cleaned up some unused files
3. ~/wrappers/csharp/CMakeLists.txt now works to build the native library, the managed assembly and install them
You could add a
if(WIN32)
  message( FATAL_ERROR "C# bindings for Windows are currently not supported." )
endif()

Instead of the todo.