This supersedes my patch from 504414 - exporting the mediadb with Artists and Album folders, and adds a controllable UPnP MediaRenderer.

It works best with Coherence >= 0.5.2, which is in svn trunk at the moment and will be out as an intermediate release in the next days, so there will be a corresponding package in the dists.

It should work fine with older versions, some of the new functionality in the  client and the MediaServer won't be there, and the MediaRenderer will not be activated. But apart from that it won't lose existent features.

Open issues:

 * rb doesn't detect album art served by a MediaServer
 * rb doesn't export album art to other UPnP clients
 * the MediaRenderer can at the moment _only_ play files outside of rb, e.g. served by some other UPnP MediaServer. We have yet to define an 'internal' protocol type, that maps the UPnP uri send by a ControlPoint to the entry within the rhythmdb