Entities now have 'calc_rect' and 'do_tile_collision_detection' as functions.
Entities now require a size.
Tiles now come with two new variables: 'solid' and 'deadly'.
Added WallTile class.
The Player now collides with the new WallTile class.
Changed the colors of all tiles.
World now generates random dungeons.
World now adjusts the camera position so that it prefers the center of the dungeon, but will move to show up to 200 pixels around the player.