Room name randomizer doesn't increment correctly

[tmcclintock]

The AlphaNumRoomName is used to name Rooms being put in the dungeon. It is supposed to name room A0, B0, ... Z0, A1, B1, etc. in that order. However it is bugged because it generates names for rooms without knowing if they get put in the dungeon (e.g. they may overlap and get rejected).

This is a bug.

The fix is the following: the AlphaNumRoomName.randomize_room_name should take the dungeon as an argument. It should store a name and keep trying to use it unless it is in the dungeon.rooms dictionary, in which case it generates a new name.