I tried to start generalizing some world classes. Keep a list of
drawables, collidables, updatables... so that when you need to draw,
just call .draw on all Drawables, etc.

Switch blocks not quite there. Some parts are sloppy... but def getting
closer. Feel free to hack away or I'll take a look on Saturday.
Generalized a lot of stuff. Made drawables/updatables/collidables. Also
tried to make blocks more spread out (instead of all in one class) and
made tilesheets based on the tile manager
Merge remote-tracking branch 'origin/generalizing_cleanup'