Make level use correct object definition
MazeGenerator no longers adds padding walls
Added Room class for generating specific types of rooms
Merged Room and RoomPlaceholder classes
Removed checks for 'valid' rooms
Added handling for up and down stairs
Monkeying with Main
Dungeon generator places rooms semi-intelligently, and overlays the map from the room
Merge branch 'master' of https://github.com/Asmor/python-roguelike