- Remove mysterious restriction in visibilityhelper for gameobjects
- Some cleanup in CheckAreaExploreAndOutdoor() and GridDefines.h
- Set nocreate for cells visited in Map::VisitNearbyCellsOf
-Drop condition CONDITION_SPELL_SCRIPT_TARGET, use other condition types instead
-Change CONDITION_SOURCE_TYPE_SPELL_SCRIPT_TARGET to CONDITION_SOURCE_TYPE_SPELL_IMPLICIT_TARGET:
--allow using this condition for more spell implicit target types (not just ENTRY)
--SourceGroup value for this src type is now effMask and it's now required
Core/Spells: Unify the way implicit targets are handled, fully implement some partially implemented target types, fix some minor bugs found on the way, general improvements and cleanup.
Note: The naming of classes is still confusing. "cell" usually refers to class "Grid", and "grid" usually refers to class "NGrid". But it requires a lot of changes to clean this up.