This allows to properly fixup (upgrade) RoomStatus structs
restored from a older format save in an upgraded game.
For example: game was upgraded from 3.4.0 to 3.6.0, but player
tries loading 3.4.0 save. In this situation the engine must know and
keep track of what version each RoomStatus was saved in.
This is necessary, because RoomStatus can only be updated upon
loading a corresponding room file (when entering a room). This
means that multiple RoomStatus objects will be staying in memory
not being upgraded yet, until player enters particular room.
From upstream 205232af5909e0a257494ff404f36003b004ebc4
Walter Agazzi
Thierry Crozat
D G Turner
Paul Gilbert
Eugene Sandulenko