Complete overhaul of loot system + fix DND

Group loot works mostly correctly but quest item priority is not
implemented (quest items can still be looted once loot becomes available
to all)

Round robin works perfectly

Master Looter works perfectly

Free for All works perfectly

Need before Greed is untested, but should also work

Players should no longer have items get stuck on "This item is still
being rolled for"

Master looter icon should no longer appear when not using Master Looter