Switch from libjcsi to GameWorlds

Switched over the weekend, failed to remember to commit. This morning I
got annoyed with my code
(that wasn’t working at all and was so messy I couldn’t figure out why)
so I started over.

Still needs:
-Collision detection [Thing&Dodger] (+ corresponding fail state)
-Score ( = # of ‘Thing’s dodged, probably)
-Collision detection [Thing&Thing] (+ corresponding response and fail
state)