durcyn:
	- ignore higher level preview spells when scanning the spellbook
	- interrupt detection works, now show a bar for it
	- clean up INTERRUPTED handler
	- slightly less shitty interrupt handling
	- AceEvent doesn't handle RegisterUnitEvent?  use RegisterEvent with an ifcheck on the function for now
	- attempt to do something meaningful with UNIT_SPELLCAST_INTERRUPTED to prevent bar spam on interrupts
