events.go
func (e *EventLog) Printf(format string, a ...interface{}) {
	newfmt, newvals := addEvent(e, format, a...)
	Log.Printf(newfmt, newvals...)
	e.el.Printf(format, a...)
}
func (e *EventLog) Printf(format string, a ...interface{}) {
	newfmt, newvals := addEvent(e, format, a...)
	Log.Printf(newfmt, newvals...)
	e.el.Printf(format, a...)
}
// Printf formats its arguments with fmt.Sprintf and adds the
// result to the event log.