[DONE] Add indication whether controller callback was successfully disconnected

[Swiftb0y]

While Mapping the NS6II, I encountered a problem where I had to check if the connection is already disconnected.
The added code will set connection.isConnected to true/false accordingly. It will also return whether connection.disconnect() was successful.

TODO:

• Add tests
• Add Wiki Documentation

[Be-ing]

Nice idea. Would it be better to add a conn.isActive or conn.isConnected property instead of adding another meaning to the id property?

[Swiftb0y]

It would make more sense yes. I just thought using the id would be fine since it has no real purpose in mappings right now. Also isConnected would IMO hint that it was possible to reconnect a disconnected "callback object". Regardless, you are probably right that a dedicated property would be the better choice.

[Be-ing]

Looks good to me other than the tab character noted above. Thanks for working on this and documenting it. I think it will be useful for debugging controller scripts. I edited the documentation you added to the wiki to note this will be new in Mixxx 2.3.