Added direction parameter to Creature constructor

Part of #40
Refactored bullet, crate, and creature to have a common entity base
class.

Part of #40.
Moved State.health into player class.

Also fixed typo in creature.

Part of #40
Removed display inventory from player and added inventory screen on 'i'
press in main loop

Part of #40
Move images to res folder
Fix a few more image paths
Merge branch 'master' into nhandler-res

Conflicts:
	game/src/crate.py
	game/src/gameScreen.py
Added interactive inventory screen