Core/Vehicles

* Fixed crash happening when passenger died on vehicle he was controlling
* Fixed crash happening if vehicle control aura was removed before passenger is fully added to vehicle

Closes #7160
DB/Quests: Fix The Best of Intentions, closes #5716

Remove a bunch of incorrectly spawned NPCs and add some missing NPCs and GOs for quest Defiling the Defilers.
Script/Spell: Unlocking Zuluhed's Chains

Closes #996