Uploading raylib-umka to UmBox

[marekmaskarinec]

I know this library is not actively maintained, but I think it would be nice if it was available through UmBox.

UmBox is Umka's own package manager, which we've been working on for a while and which is very close to being released.

[RobLoach]

I'm down for it to be on UmBox. I don't reallly have any capacity to take it on though. Would you liek to help in pushing it forwards? I'd be happy to add you as a contributor on the repo.