Seconds since the last call to lapse, without resetting the lapse counter

Property definitions

realtime $ Clock :: peek_lapse
	# Seconds since the last call to `lapse`, without resetting the lapse counter
	fun peek_lapse: Float
	do
		var now = temp
		now.update
		now.minus(now, time_at_last_lapse)
		return now.to_f
	end
lib/realtime/realtime.nit:219,2--226,4