* Add native support for pulseaudio.
This adds ability to get Pulseaudio current volume without calling an
external program. Also it provides a few other parameters like card's
current profile similarly to pavucontrol. Currently it only queries the
default sink (and associated card).
* Switch to pulse async API.
This us by far the most efficient as conky subscribe to a few pulseaudio
notifications. Whenever pulseaudio server changes (volume or default
sink or default card), conky's callback updates the results.
