Add constness to AnimatedSprite::render

Should have been const.
Made Door renderable via AnimatedSprite
Parsing animation/image for Doors in MapLoader
Added updateDoors() to GamePlayState
Fixed door rendering in MapRenderer
Made "entrance" solid in test map 4, room 1
More tweaks to test map 4
Fixed wrong door updates in GamePlayState
Adding statefulness to doors
Added more realistic doors
Using default syncgroup for door animations
Redrew door graphics to make it more accurate
Always rendering doors, disabled debug door rendering
Added door test map, clean up code
Merge pull request #120 from zackthehuman/master

Doors implemented.