v1.3.0 — Meter reading start time

What's new

• GwStatus.meter_since: start of the current meter reading on gas and water devices, as an aware UTC datetime (meterSince of the gw block, firmware 1.3.0). It is the time of the first reading entry or of the last meter exchange; a correction of the reading keeps it. None on older firmware or when unknown. Suited as last_reset of a total sensor.

See CHANGELOG.md for details.