Fix setting output/device for Xine and VLC backend

- Fixed setting output and device on Xine and VLC backend
- Fixed track slider for Xine, VLC and Phonon
- Improved backend settings to better support multiple backends
- Added group by samplerate and bitdepth in collection
- Fixed crash on exit when existing instance of the application is already runnung caused by NVIDIA driver
- Changed Q_OS_MAC to Q_OS_MACOS

src/playlist/playlist.cpp

@@ -1127,7 +1127,7 @@ QString Playlist::column_name(Column column) {
     case Column_Samplerate:   return tr("Sample rate");
     case Column_Bitdepth:   return tr("Bit depth");
     case Column_SamplerateBitdepth:   return tr("Sample rate B");
-    case Column_Bitrate:      return tr("Bit rate");
+    case Column_Bitrate:      return tr("Bitrate");
 
     case Column_Filename:     return tr("File name");
     case Column_BaseFilename: return tr("File name (without path)");

src/playlist/playlistfilter.cpp

@@ -56,13 +56,17 @@ PlaylistFilter::PlaylistFilter(QObject *parent)
   column_names_["genre"] = Playlist::Column_Genre;
   column_names_["comment"] = Playlist::Column_Comment;
   column_names_["bitrate"] = Playlist::Column_Bitrate;
+  column_names_["samplerate"] = Playlist::Column_Samplerate;
+  column_names_["bitdepth"] = Playlist::Column_Bitdepth;
   column_names_["filename"] = Playlist::Column_Filename;
 
   numerical_columns_ << Playlist::Column_Length
                      << Playlist::Column_Track
                      << Playlist::Column_Disc
                      << Playlist::Column_Year
-                     << Playlist::Column_Bitrate;
+                     << Playlist::Column_Bitrate
+		     << Playlist::Column_Samplerate
+		     << Playlist::Column_Bitdepth;
 }
 
 PlaylistFilter::~PlaylistFilter() {