Current frame-rate

Updated each 5 seconds, initialized at the value of maximum_fps.

Property definitions

gamnit :: limit_fps $ App :: current_fps
	# Current frame-rate
	#
	# Updated each 5 seconds, initialized at the value of `maximum_fps`.
	var current_fps: Float = maximum_fps is lazy
lib/gamnit/limit_fps.nit:30,2--33,45