Dement, Enfeeble and Vertigo code changes, Sickness consolidated into Debuff, new Deleted class for removed classes. Error fixed in duskrat.kod.

All three spells function the same as before, but I've taken the code from the Dementia and Palsy classes and consolidated it into Dement and Enfeeble. These two are now in class Disease which is a subclass of Debuff (solely so diseases can still be distinguished from other debuffs) and the Disease class now holds code common to both debuffs. Vertigo now contains a DoSpell function for the actual casting of the spell (so it propagates and displays the duration). Poison is now also in the Disease class, and Sickness has been moved to Deleted (just contained pieces from spell.kod).

Created a new Deleted class for dangling classes left from deletes such as this one, and moved the deleted wands there too. This seems to remove the templates for them in the game/save game, so they could then be deleted safely at a future date. As far as I know, this is the easiest way to fully delete classes, although I still need to verify that it works on 104.

Oh I did change one thing, enfeeble/dement from monsters will now last the same amount of time as that cast by players: 1-3 minutes based on spellpower (50 spellpower from lower-level mobs, 90 from thrashers).

Fixed an error caused by dusk rat poison attempting to send the waver effect to monsters when poisoning them, as the monsters obviously can't display those effects.