Update to paho MQTT 2.

Merge tag '4.2.0'

Merge tag '3.0.0'

Merge tag '2.3.0'

Merge pull request #9 from jlrgraham/rediscover-on-ha-reboot

Try to get Shelly gen 1 device to re-announce when HA restarts.

Logging, sync up with gen2.

Fix state_topic error (bieniu#245)

Fix state_class for energy sensors (bieniu#244)

Fix expire_after error (bieniu#240)

Meters kwh (bieniu#234)

* Fix use_kwh for Shelly EM and 3EM

* Fix documentation