Spell overhaul: Add new debuff class, move debuffs. Vertigo now affects monster aim/agil instead of casting Enfeeble on them.

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, 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.

Correction: I've now made two changes to Vertigo. 
1. Since monsters (as of the last update) now have aim and agility, Vertigo directly affects these (same as for players, reduces defense/offense via aim/agil) instead of just casting Enfeeble on the monster as it did previously. Players shouldn't notice a change here except that they can now cast both spells on the same monster. 
2. The wavy screen effect that Vertigo causes is called for 15 seconds if RestartEnchantment in Vertigo is called (eg. player logs off/on with the spell). I changed this to obtain the correct time remaining for the debuff, and use that time for the wavy screen effect duration instead.