public class CommonMapController.ViewStack
Maintains a list of past Map Displays that will be shown in order as sessions end.
For example, if a map display for showing on an Item Frame was set, and a new one was set
for when the player holds the map, it will 'take over' from the item frame version. Once the
player stops viewing the map again, and that session ends, it will automatically fall back to
showing the item frame version.