Add a way to undo polymorph

[Studenterhue]

They sure can SR-revived, it's just that it requires them to actually be in their corpse rather than observing the wizard or whatever, as with human corpses. I'm not sure how anyone would know that aside from looking at the wiki or something. Which adds a new sort of anxiety for any SR reanimators over whether the dead person knows to Re-Enter their Corpse so they can be revived.