added Inventory::FistsEquipped

DRY
fixed a comment typo
Actor::GetCombatDetails: apply proficiency bonuses to bypassing weapons too
Actor::MeleePenalty: fixed calculation

it was always returning 4 for nonmonks due to bad expected value and
didn't cater to all 16 combinations (monk/other*fist/weapon)

like elsewhere, monk fists, unlike default ones, are considered weapons