Move player corpses on instance shutdown

Moves corpses to graveyard when an expired instance shuts down.
Zones without a graveyard move them to non-instance version instead.

Fixes player corpses being left inside instances that expire
before graveyards process or in instances without a graveyard

zone/entity.h

@@ -537,6 +537,8 @@ public:
 	void UpdateAllTraps(bool respawn, bool repopnow = false);
 	void ClearTrapPointers();
 
+	int MovePlayerCorpsesToGraveyard(bool force_move_from_instance = false);
+
 protected:
 	friend class Zone;
 	void	Depop(bool StartSpawnTimer = false);