Map Editor Bugfix

[Bug fixes to the Map Editor]

I had changed the way character sprites were stored, but had not updated the map editor, so there were a couple of problems to fix (including crashes - sorry about that!)

You should now be able to change any unit to any other class, including characters that are NOT on their "team". Those characters will show as blank, however, so it should be pretty obvious whether or not you should use that character or not.

Any more bugfixes/suggestions please let me know at your earliest convenience, thank you.