Fixing Group Loot Issue

- Everybody within a group will be able to loot any creature which is dropping a shared quest item
- Everybody within a group will be able to loot any creature which is dropping a starting quest item (if it drops at 100%)
- When a player release the corpse, other players of the group will be able to loot the creature as well (except if a member was not part of the group before the kill)
- Respawning creatures won't appear with a grey bar anymore