Added direct support for Shelly Gen2+ devices

[jjdejong]

It was somewhat awkward to have to use something like Node-RED to map the Shelly MQTT data to the format required by the original driver. So I coded a direct support for my Shelly devices.

[mr-manuel]

Why are you not using https://github.com/victronenergy/dbus-shelly/?

[jjdejong]

Why are you not using https://github.com/victronenergy/dbus-shelly/?

Only supports the very specific Shelly Pro EM devices that use a totally different JSON payload. I tried to adapt that, but didn't succeed.

[jjdejong]

By the way, this code also merges some reformatting from a 0.18 fork that wasn't in the main branch. In fact a lot of the changes are just reformatting, so it may be confusing as to what effectively changes... I can remove the reformatting if you prefer.

[jjdejong]

OK, removed all the code reformatting. Only the essential changes are visible.

[mr-manuel]

Thank you for your contribution. I simplified the integration a bit, so no extra config is needed.

[jjdejong]

Thank you for your contribution. I simplified the integration a bit, so no extra config is needed.

Cool, by detecting "apower" in the JSON payload ;-)