NEXA 2000 updates

[s-hoffleit]

I finally got the holding and config registers working for the NEXA 2000.
I still need to test them a bit more. I found some more registers where I don't know yet what exactly they do/mean but will try to find out

[robertzaage]

Morning, is this still a draft or already in a mergeable state? 😄

[s-hoffleit]

The changes are theoretically mergeable but there are still some registers I would like to add next week when I come around to doing it.
So if you want you can merge this I'll open another pull request, otherwise I would have added it to this one.

[robertzaage]

No pressure, just take your time 👍🏻

[s-hoffleit]

I finally got a smart meter to work. I'll need to look at it pairing again with dumps enabled to see if it does something else.
As there is not much sun here and the battery is empty again I'll need to repair it tomorrow to look at the dumps.
Register 324 seems to be the safety margin for the smart mode but I somehow can't set it from the ShinePhone app.

And what exactly is the reason for changing the topic from s/... to s/33/... as explained in client.py:403 ?