Alert other NPCs in range

[WoutProvost]

When an NPC aggroes a player for the first time, alert other NPCs in range.
Alternatively, when the NPC has a target, it will alert any other NPCs in range, until the encounter ends.

Maybe both can be implemented using an enum in which 3 types are defined:

• don't alert
• alert on first aggro
• alert until encounter end

Also need functionality in which we can toggle responding to this alert on or off.