NPC Combat Enhancements

NPCs can now use abilities, set in their spawn file.  After money, place
%ability and then the name of the ability once for every ability the NPC
can use.
NPCs' decisions are now unique. After abilities (or money, if there are
no abilities) place %useattack and then the rate the NPC will choose to
attack, then %useability and the rate the NPC will choose to use an
ability.
Do not set %useability to 100 if the NPC has abilities that cost mana or
hp (will forever attempt to find an ability it can afford to use once
its mana/hp gets too low).