Expand Magic Mastery to other skills

[Bakelt]

Add magic mastery as a synergy multiplier to other Magic damage based skills. See Necro bone skills for how it is handled. It needs to be added manually as a synergy because the stat itself is not functional.

Currently, the only source of Magic Mastery / "+ to Magic skill damage" is Blood Golem but there is an oskill Blood Golem chest and we may add more items in the future.

Magic Arrow
Holy Bolt
Fist of Heavens holy bolt missile
Blessed Hammer
Berserk
Psychic Hammer