Polymorph can now be temporary for monsters, similar to the player.
Player monsters will revert to normal form like the player after being killed in polymorph form, while for other monsters can be killed normally in polymorph form.
Polymorph-causing items can now have a custom duration, and it is displayed in examine; the normal duration of potion of polymorph has been doubled from before, and breath duration halved from before.
Polymorph spells have now custom durations; the durations of polymorph self and shape change have been increased.
Killing monsters via transforming them into green slime now counts as a kill and yields experience.
Several fixes and improvements related to Gnoll Overseer.
Added game state debug information to impossible and panic.