TODO-569: crude dead-reckoning running
TODO-569: crude dead-reckoning running

Typical run is 1400 to 1500 ticks
(128 ticks = 1s, so 1 tick ~7.8ms)
with closing taking longer
(against the valve spring)
than opening.

Min run period to avoid false end-stop reports
is ~30ms or ~4 ticks.

Implies a nomial precision of ~4/1400 or << 1%,
but an accuracy of ~1500/1400 as poor as 10%.
opentrv/opentrv,opentrv/opentrv,opentrv/opentrv,opentrv/opentrv,opentrv/opentrv