#313 Private Property: game crashes

[Bob Chamot]

The game crashes as reported at https://sourceforge.net/tracker/?func=detail&atid=101997&aid=1568128&group_id=1997. According to treellama, "This is a corrupt map. Polygon 12 is type 7, a platform on trigger, but the permutation for that polygon (which ordinarily would say which platform to trigger) is -1. Aleph One tries to look up the platform in polygon -1 and asserts out."