Armor Break fixed & updated

Fixed a bug causing Armor Break to have no effect
Armor Break potency decreased:

15 + L*(St/7 + De/10) --> 10 + L*(St/12 + De/15)

Updated the AI decision making on when to use Armor Break.
Fixed a bug calculating damage mods from affinities.
Enemy targeting AI now takes stances & affinities into account when calculating lowest effective health, not just armor.