Ability re-vamp and new stat

Intelligence is now a stat.
Agility has been renamed to dexterity.
NPCs now have levels.
Innkeepers' costs are equal to 10*their level.
Abilities can now influence multiple stats at once.
Abilities can influence each of those stats by different amounts (with
different defending amounts).
Abilities can now have unique functions assigned to them in the style of
NPC reactions. The old ability type has been moved into the StatMod
function.
Only StatMod functions (currently) initiate combat in the overworld.