Implement SFC 46 "STP"

Signed-off-by: Michael Buesch <m@bues.ch>
Implement "clock memory"

Signed-off-by: Michael Buesch <m@bues.ch>
linuxcnc: Catch maintenance requests

Signed-off-by: Michael Buesch <m@bues.ch>
tests: Stop CPU at the end of the tests

and remove default --onecycle option

Signed-off-by: Michael Buesch <m@bues.ch>
Add clock memory test

Signed-off-by: Michael Buesch <m@bues.ch>