Fix #1976: Prevent GIDL from moving

The GIDL is now C4D_Living and C4D_StaticBack, preventing it from moving. At first I thought that adding an underground vertex would be sufficient, but that still made the idol move/shake when hit.

planet/Defense.ocf/FightForGidl.ocs/Script.c

@@ -152,7 +152,7 @@ func StartGame()
 	// Init objects to defend
 	for (var obj in [g_statue, g_doorleft, g_doorright]) if (obj)
 	{
-		obj->SetCategory(C4D_Living);
+		obj->SetCategory(C4D_Living | C4D_StaticBack);
 		obj->SetAlive(true);
 		obj.MaxEnergy = 800000;
 		obj->DoEnergy(obj.MaxEnergy/1000);