Lots of work on the new playlist control.

- PlaylistListViewControl: Fixed bugs in rendering cells, now displaying
album art correctly. Also added song length. Artist name and album title
are now on the same line. The currently playing song is now updated.
- SessionsPlaylistListView: The contextual menu can now be opened. The
song can be played by double clicking on the cell.
- IPlayerView: RefreshSongInformation now adds the currently playing
playlistItemId.