calling execute() every tick

Yeah. I've cleaned up and compartmentalized the initialization code some more, and after some reading about Exception catching, I'll probably try to catch problems there so I can at least get a console message when something screws up.

I just started my static Universe, Gun and Wheels as nulls, and initialize them if they're null. That prevents the need to check what getRoundNum() it is. With everything spread out, bug hunting should be easier!

Thanks for the help and encouragement, folks! :)