Introduce min_event_systime and rework the previous start_time,
last_event_time, and event_running flags into this one state tracking
variable.
This also makes a minor change to the behavior of the event_delay - it
is now calculated from the time the command completes execution
(instead of from when the event is first detected). This may make a
difference if there is a long running g-code command occurring during
the detection event.
Signed-off-by: Kevin O'Connor <kevin@koconnor.net>
b6368173cf