Fixed not iterating over difficulty variants. Now the mod will actually work.

Added some more classes to the WTFClasses list (shiv classes, viper classes, some more unused LWOTC classes...)
Added a new heuristic to auto-detect classes that should go into the wtf class list, courtesy of Zelfana.

Added resistance rebels, playable aliens and mec troopers from lwotc to the list.
When used with LWOTC, the four base classes should be ignored automatically.
Added logic to automatically detect classes not meant for normal soldiers - classes that have non-empty or non-soldier "RequiredCharacterClass" or "AcceptedCharacterTemplate". Such classes should be ignore.
Use the PrintClasses console command to see if there are still classes that should not be there.

Changed TruncateBrig config option to be false by default.