Run time calculation in g-code program properties

@Kostas,

Very interesting.

Problem can be : no existing encoder or PWM blocks in the HAL.
I think seperate program timer solves the problem. But can also be calculated in program left time in ngc section i think.

It's a problem they know before on IRC : wiki.linuxcnc.org/cgi-bin/wiki.pl?SimpleCycleTimer

www.gano.name/shawn/CNC/files/6c85b2f279...e735ded9b4deb-0.html
www.linuxcnc.org/docs/devel/html/man/man9/time.9.html
linuxcnc.org/docs/html/hal/components.html