Spell overhaul: Add new debuff class, move debuffs.

This pull request creates a new class of Spell called Debuff, which contains the following single target offensive spells: Blind, Dazzle, Dement, Mark of Dishonor, Enfeeble, Forget, Hold, Purge, Seduce and Vertigo.

Individual files have been edited to remove excess whitespace and grammatical errors, and spell descriptions now show the exact reagents required to cast these spells. There are NO CHANGES to how these spells operate, but this will allow future improvements to be put into separate pull requests rather than combined with a general file move.