Heavily rewritten MapDataFile & Tile handling

Rewritten much of the Tile handling code, tiles now stored in
GameDataManager like TableParsers; implemented INotifyPropertyChanged
for tiles, made tiles edit- and saveable; rewritten FloorMapEditor's map
drawing code to pre-generate map bitmap, to partially regain performance
lost when moving Tile instances to GameDataManager; more testing and
potential performance regaining needed; other minor changes and
renamings