Fix Invert by Barbarian
Fixes a bug in the logic of the September 2002 Tribes 2 patch in the invert code--basically, if you played inverted normally and inverted in vehicles both, the both being inverted negated each other and made it non-inverted. For use with the Sept. 2002 patch ONLY and also any subsequent patches that don't work. Code ripped from Crunchy's PilotMode, so heavy credit to Crunchy.