Remove boss/slaves keeping aggro when offscreen
Description
Make the boss/slaves lose aggro when the player leaves the screen while attacking them. The way it works now is that if I'll SG lets say a Phreeoni, kill her slaves in the process and leave the screen, she may resummon her slaves who will come after me even though I don't see Phreeoni/slaves. Phreeoni won't come after me like that but she may aggro instantly when I'll enter screen range instead of proper aggro range.
Rationale
I'm not an expert on vanilla behavior but a friend of mine told me it's not a vanilla behavior. Supposedly it used to be normal until around 2nd classes were introduced on oRO. This weird mechanic hinders a lot of classes like HW or Snipers.