syntax highlighting support for CUDA C++ .cu / .cuh files

[eduidl]

related issue

#535

reference

https://docs.nvidia.com/cuda/cuda-c-programming-guide/index.html#c-language-extensions

---

CUDA is extended c/c++, and necessary change is three, I think.

Function Execution Space Specifiers

__device__, __host__, __global__, __uninline__, __foreceinline__

ex.

__device__ kernel_func(int a) {
  // do something
}

Variable Memory Space Specifiers

__device__, __constant__, __shared__, __managed__, __restrict_

ex.

__constant__ int i = 1;

Built-in Vector Types

char, short, int, long, longlong, float, double and dim3

[dblessing]

One minor comment, otherwise looks great. Thanks @eduidl

[eduidl]

I found demo code has error, and correct it.
However, I mistook author of commit because of using office's PC....

[dblessing]

@eduidl

However, I mistook author of commit because of using office's PC....

Do you want/need to change that before I merge? You can pull the source branch on your personal machine and run git rebase -i master and squash/fixup commits into one logical commit. Then, force push to your branch to update this PR.

[eduidl]

@dblessing

Thanks for your kind offer. I appreciate it.
I have finished squash, so please merge anytime!

The change has been made and the issue resolved.

[pyrmont]

@eduidl Sorry this took so long to merge in but thank you for the pull request! It's great to have an additional lexer for Rouge :)