Bugfixes

General:
- Fixed a bunch of random lua errors using the Object manager.
- Added a completely new cache to properly keep track of how many units
we are in combat with. This hopefully fixes the random nil comparison
lua errors as well. More testing needed.

Warlock - Destruction:
- Added Immolate on mouseover.
- Fixed a bug where Immolate sometimes wouldn't cast on your current
target.