-Completely Invisible Heads now require that the Character be a Soldier, Reaper, Templar or Skirmisher. The upshot is that Completely Invisible Heads should no longer appear on Engineers, Scientists or Civilians.
-In order to do this, I had to make separate Invisible Head cosmetics for Reaper and Templar (the Skirmisher head was already separate).
-There is now a slider option for CompletelyInvisibleHeads in the Game Options menu (same place as all the other DLC content sliders).