Sequencer item property handling.
This is just a subroutine function for X2PreSpellCastCode, which handles the whole process of storing spells into a sequencer item.
To make an sequencer item, just give it cast spell item property with one of three sequencer's spells.
If you change it, such as to allow hostile spells, you will need to recompile all default spellscripts to see changes.
author: ShaDoOoW, editor: Mistress, Kookoo