Development: adding homie
I want to add homie for mqtt (as well as mqtt).  This supports discoverability for home assistant and openhab (2.4 mqtt).

So I think https://github.com/mjcumming/HomieV3 might be a good one to integrate...mostly because it's v3 which is what is needed.

I think the best way to do it, it to create a copy of the MQTT_Interface.py and modify it.

But the main thing that is needed, is a list of all the 'things'  that can be utilised.  If I can read the code properly, the MQTT_Interface is only called when there's a value change.  Is there a global registry of zones/partitions etc, or will I need to update the main classes so that when reading the items labels from the panel that Homie_MQTT_Interface is called to create all the items so they can be advertised.

