Various fixes 2

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.