add an option '--except'

-x PATTERN_EXCEPT, --except=PATTERN_EXCEPT
	a vertical bar (|) separated list of lua patterns for which this
	program will not search. this program will try to match this pattern
	with timestamp excluded text. ( "[MM-dd mm:ss] blah" -> "] blah" I
	recommend you to use this like '-x "^[%p%s]*NICK[%p%s]"'. see
	LUA PATTERN for details.