Check whether a spell needs channeling before triggering unequip (#65)

[sorsarre]

Hi. Trying to bash on #65 here. Currently the unequip-before-cast option unequips both hands for all spell types despite channeling being needed only for Magery and Mysticism spells.

• Added SpellKind property to Spell that indicates spell type (Magery/Necro/Mastery/etc)
• Made unequip-on-cast trigger contingent on the spell being from a school that needs spell channeling (e.g. only magery and mysticism at the moment)
• Re-written Spell.Name property to looking at spell type instead of raw circle number.

[markdwags]

Thanks for the PR!