Created compiled version with mypyc

[sobolevn]

It would be awesome to have a pre-compiled C version of returns.
It think it might be possible with mypyc.

This way we can try to achieve really fast code for users.

[thepabloaguilar]

I think we have to take a look in the entire project (returns) before doing this, I'm looking to the mypyc's issues and they are kind of worrisome:

• Decorated function __name__ incorrect
• Make multiple assignment faster
• Make tuple equality faster
• Exception catching is slow

Actually 30% of the open issues is about speed. Using mypyc can be great or bring some trouble.

[sobolevn]

mypyc/mypyc#586 was not released in 0.780