[CRASH] 0 Strength melee crash bug fix

lldb drops EXC_ARITHMETIC when melee-hitting things with 0 strength.

simple steps to reproduce
1) start with 4 str char
2) wish for poisonous mushroom (grab all 3, eat all 3)
3) proceed to smash things with a weapon

Did not check for other occurrences, hopefully this fixes a few of them melee crashes.