Improvements to the automated generator script

- Solved error with limited identifier length.
  That was in fact an issue with cpp. For some
  reason using cpp-4.7/cpp-4.6 and so works fine.

- No need to tweak cuda.h manually now, it's all
  happens automatically now.

- Added utility script to re-generate both header
  and implementation file.

TODO:
- Constants which are define'ed, they're totally
  missed at this point because of cpp preprocessor.
- CUDA GL interop API.
- Automatically find cuda.h, currently it requires
  to be in the same folder as the scripts.
- cuda_error_string() is not implemented.