Bug Fixes in Multimedia
MetaProxy::Track::playableUrl(): don't return uid url
...when the underlying track is not loaded (yet). We return false to
isPlayable(), so we shouldn't be returning anything either.
URL may be something like amarok-sqltrackuid://2f9277bb7e49962c1c4c5612811807a1
and Phonon may choke on such urls trying to find a codec and causing
* Fix hangs and inappropriate messages when trying to play a track from
a saved playlist that has been deleted in the mean time.