Undo stack has potential to run out of memory

[GoogleCodeExporter]

There is currently no limit on the number of actions that can be undone.
The undo stack stores a complete snapshot of the tile id's of every tile on
the map every time any editing is performed. When editing a large map over
a long period, there exists a high chance for out of memory exceptions so
occur.

Original issue reported on code.google.com by [email protected] on 29 May 2008 at 11:00