Change MQTT message size with additional 200 characters
Allow clean disconnect as optional. This avoid the automatic deletion of LWT message in the broker for clean disconnections, in order to let LWT work also on all cases (Restart, Config Changes, etc) See https://github.com/arendst/Tasmota/issues/7189
6.5.0.15 20190606 * Change pubsubclient MQTT_KEEPALIVE from 10 to 30 seconds in preparation of AWS IoT support