Determines the spell that was last cast.
This is for use in a OnSpellCastAt script, it gets the ID (SPELL_*) of the spell that was cast.
It will not return the true spell value, but whatever value is put into the EventSpellCastAt() - therefore, sub-dial spells like Polymorph will merely return SPELL_POLYMORPH not the sub spell number.
You should not use this function in actual spell scripts. In spell scripts, use GetSpellId instead.
author: Jody Fletcher, editor: Jasperre