Config Flow, sockets and code rework

In this release, there's a bunch of code quality improvements, particularly around socket handling. The big functional change is a rewrite of the config flow, particularly around Discovery. If you were using Discovery previously, it basically ran the discovery each time you start, rather doing the discovery in the config flow and saving the resulting config entry. That was just nasty, so I've redone it. The downside is that if you're using discovery, you existing entry doesn't actually contain any data - just a flag to discover. So, you'll get an error message telling you it's deprecated and to delete and re-do your discovery. The entity_id should remain the same when you do this, so all of your automations etc. should still work fine, but as ever - do a backup first.

If you don't fancy doing this, wait for a later beta when I'll have a look at seeing if I can make migration work.