Cooperative groups support.

[csarofeen]

Remove whitespace on empty lines.
Add support for cooperative groups.

[maddyscientist]

Thanks @csarofeen, good to have coop support. A couple of quick things:

• Can you add an example of using coop_launch to the jitify_example.cpp code?
• I know @benbarsdell prefers tabs over space indents. So we should keep it consistent.

[csarofeen]

Good point on the whitespace. I'll start working on an example.