[TW109] Scripts/Spell: Roar of Sacrifice

- Pet that cast spell receives 20% of damage taken
- Move SPELL_AURA_MOD_ATTACKER_SPELL_AND_WEAPON_CRIT_CHANCE crit chance
calculation outside SPELL_DAMAGE_CLASS_MAGIC. Hopefully no unforeseen
consequences.
Merge pull request #78 from gecko32/TWP7

[TW109] Scripts/Spell: Roar of Sacrifice