Revisit the scene system

[aeturnum]

Currently scenes rely on the room name string to index them. That means that each room is unique in a scene and needs to rely on various state tricks to change in behavior if the player visits them again. On one hand, this forces designers to think seriously about rooms - rooms that are different really should be tracked by different objects. On the other hand, it makes certain common transitional rooms in the normal adventure format (in a tunnel, X over there, Y over here) somewhat frustrating to maintain.