Returns id of the owner of the turret. On clients always returns 0.
Some info on turrets: A vehicle turret will change locality when player gunner gets in it, just like vehicle changes locality when player driver gets in it. Many commands for turrets work only where turret is local. When gunner leaves turret it is supposed to change locality to the locality of the vehicle. A vehicle can have one owner while turrets have different owners.
Run on server in MP.