grep for spiker.ana_offset, remove instances

discrimination modes:

ttl:
	one of the A/D channels must be set to 'ttl'

window:
	window_channel must be set to the channel you want to do window
		discrimination on
	spiker.channel(window_channel) can be set to anything ... it will still
		work.
	damnit, what if they don't want to save that channel?
	adapt spiker_getTTLbuffer()  to return proper channel when detect.mode
		is window

