heating should be on only if actual recent avg temperature is less than wanted temperature
heating should be on only if actual recent avg temperature is less than wanted temperature

this is meant to deal sensibly with situations where sensors
are not available (e.g. out of battery) or can't talk to
the ninho's BLE adaptor for whatever reason. an average of the
latest recent temperatures is used and if no recent readings
are available at all we assume that we should keep heating off.

this way, we avoid keeping heating on indefinitely in case of
sensor or other ninho hardware/software failure - if people are
away, the failure won't matter and keeping heating off even
in cold weather wouldn't matter (but we'll need to deal with
freezing points etc. later on), whereas if people are around
and feel cold, they could force heating to be on by excluding
ninho's actuator, or try to fix the issue.

getninho/ninho,getninho/ninho,getninho/ninho