Feature request: spindle_up and spindle_down time delay.

[RDS356]

In my though this feature must be on sender(like mach3, Bcnc, etc) and not in firmware. I also though that the working is simple; When M3 or M4 enable respective pin and wait spindle_up in ms for executing gcode or joging. When M5, disable and wait spindle_down in ms too.