Switch to side-by-side view

--- a/cdbrowser.h
+++ b/cdbrowser.h
@@ -49,7 +49,7 @@
     void onSliceAvailable(const UPnPDirContent *);
 
  signals:
-    void sig_tracks_for_playlist_available(MetaDataList&);
+    void sig_tracks_for_playlist_available(const MetaDataList&);
 
  protected: