Revert trigger polyhedron change

Reverts the change made in
https://github.com/GarageGames/Torque3D/pull/511.  See
http://www.garagegames.com/community/forums/viewthread/136033 for the
discussion.
Merge pull request #573 from DavidWyand-GG/TriggerFix

Revert trigger polyhedron change