Extend output of `pactl list short sinks` with `volume`, `mutestate` and potentially `description`

To allow effective scripting of pulseaudio the current implementation is only focused on setting things, but not getting things.

So my first idea was to add getter functions ( see #660 ). But it would also be really nice to (potentially instead?) add all crucial information in ONE place in a consize format(!).

So I am suggesting to extend the output of pactl list short sinks with common and important sink-status information:

• mute-state : (muted|unmuted)
• volume(s) : smart volume indication: 1 value if all channels are the same (mostly!), otherwise 1 value for each channel (e.g. 50L 50R 50F 50C ...)
• default-sink : not sure if this info is already given, but this is an important info as well

Potentially also:

• description : human readable name of sink

To avoid breaking existing parsing scripts these could be added to the end.