Add: Crust

[conqp]

I'm not sure if this has become an established term meme yet, but it sure has the potential to become one:
Crust is Rust, but written like C.

The rules of Crust are:

• Every function is unsafe
• No references, only raw pointers
• No std, but libc is allowed
• Pointers are mutable by default

[Enet4]

Well, it may be nice to have that indexed. Feel free to send in a pull request.