EMI: costume fixes

This patch series fixes a crash in the final scenes of EMI:

When the actor guybrush changes its costume back from monkey robot (used during the final Monkey Kombat) to its standard costume, the game crashed since the head couldn't be attached to the actor (the monkey robot costume was still considered the current one).

Changes:
- don't load costumes if only a nil chore is set (used to unset the chores)
- removes the costumes in StopActorChores (based on its boolean parameter)

I'm not 100% sure about the logic, it contains some guesswork. It would be great if this patch series would get some testing. I'm looking forward to get feedback. ;-)