Party-based abilities

[pibedetorres]

This feature is somehow already implemented, as upgrades like "HP Reduction" and "Time Extend" against mobs, plus some others TreasureSpawns-related are passed on to the other member of the party (the upgrades with the higher level among the two players are taken in consideration). Plus there's an Ascension upgrade that raises XP and gold earned in battle while in party.