Temple: Implement contingency plan for no MP

Temple will now use an alternate attack pattern if he runs out of MP for
his usual magic-focused one.  Also fixed a regression due to the recent
status fix where Zombie would not transition to Skeleton at 0 HP;
because the engine considered the unit dead at 0 HP, the Skeleton
affliction was being suppressed.

Also updated Subzero damage to be based on Rank and implemented a new
status and corresponding skill: Curse, which prevents status buffs from
taking effect for 5 turns.