Lift the check for facing your target out of Spell::CheckRange.

Whether the caster is facing the target or not has nothing to do with
whether the target is in range. CheckRange returned early for spells with
SPELL_RANGE_IDX_COMBAT, skipping the facing-target check.

Also remove code that allows spells triggered by auras to be cast
regardless of range, reverting part of [z0555].

This fixes cmangos/issues#384.