Update Multi-Light list only when Refresh button is pressed

Updating the light list constantly as we were doing, would prevent 3Delight from re-rendering from iDisplay, as HOM_AutoLock variable created on idisplay_port.cpp would not let this, as Houdini would be busy making calls to updateLights() function when ROP was open. Maybe there could be another solution that does not cause the re-rendering problem from iDisplay and still updates the multi-light list automatically, but I could not find any.