Add support for CUDA C Language Extensions

Hello,

It would be nice to have at least one editor that decently supports CUDA Kernels.

From "Minimum File Type Info Needed":

1. The file type name: CUDA Kernel Source
2. The filename extensions that are used by the file type: .cu
3. A brief description telling what it is used for: CUDA Kernel in super simplistic explanation is the part of code that runs on GPU, providing massive parallelism and great performance in computations.
4. The URL to full specifications of the file type: http://docs.nvidia.com/cuda/cuda-c-programming-guide/index.html#c-language-extensions
5. Where specifically can the language's list of keywords, comment styles, etc. be found: It is a C language with extensions (see point 4)
6. How is the language commented, and what commenting style makes the most sense for comment/uncomment selection features: see point 5
7. Which delimiters make sense to be highlighted in delimiter highlighting: see point 6 :)
8. Links to example code for the file type: http://docs.nvidia.com/cuda/cuda-c-programming-guide/index.html#kernels

Best Regards,

Mateusz Szubart