Various fixes 2

Baldur's Gate: Dark Alliance II

An old-school hack-and-slash action RPG awaits! Pick one of five heroes, defeat monstrous enemies with weapons and spells, loot treasure and level up in this classic D&D fantasy adventure.

Resolve competing input between mouse and gamepad on shop main menu. Ensure pooled gold purchases in coop mode don't result in negative gold balance for either player. Fix crash accessing shop after start of Act II in extreme mode. Fix unlocking the 'Maximum Fun' and 'Feats don't fail me' achievements. These will be awarded retroactively on first bootup post update if save files that meet the conditions are still present.