Merge branch 'Headhunter' into 'master'

Headhunter

Headhunter I.D. Challenge Feasibility adjustments:

Spawns demoted to random_elites (with 2 classes, drop 2 rares).

Killing a target spawn causes all other NPC's to pause and untarget the player.

Npcs lower than elite rank, or summons from a target spawn, may be killed without failing the quest.

Spawns may be killed by party members or summons of party members, otherwise the quest will fail immediately if a spawn is killed by something else, or if the player exits the level.


Fixed a bug in Mirror-Match boss placement.

See merge request !385