Drop all non-standard discovery methods

[balloob]

I think that we should drop all non-standard discovery methods. All those one off discovery methods are starting to creep into this package and we end up with a ton of different implementations. I don't want to support that.

So let's remove them. We will just stick with mDNS and SSDP.

A lot of these one off discovery protocols are driven by Home Assistant. Home Assistant no longer requires these to be in netdisco, as with Config Entries we already support the integration itself doing a discovery. The main difference is that a user has to click on something like Squeezebox instead of getting a notification we found Squeezebox. This could be solved by enhancing config entries, this is something that should be discussed in the architecture repo if people are interested in this functionality.

[petri]

How about just using Python entry points to make it possible for contributors to provide whatever discovery mechanism they want as a automatically discoverable plugin package, without bloating up netdisco?

[balloob]

Netdisco was initially build for the purpose of Home Assistant. We are going to change how we do discovery in Home Assistant (home-assistant/architecture#121), and will probably even stop using netdisco, only having things be specified in HA how to be discovered. So I guess we can actually close this issue and just keep the limitation in place of not merging any new discovery methods.

If someone feels the urge to continue with a single package to discover everything, they can fork the project.