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/engine/phononengine.h

@@ -1,18 +1,22 @@
-/* This file is part of Strawberry.
-
-   Strawberry is free software: you can redistribute it and/or modify
-   it under the terms of the GNU General Public License as published by
-   the Free Software Foundation, either version 3 of the License, or
-   (at your option) any later version.
-
-   Strawberry is distributed in the hope that it will be useful,
-   but WITHOUT ANY WARRANTY; without even the implied warranty of
-   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-   GNU General Public License for more details.
-
-   You should have received a copy of the GNU General Public License
-   along with Strawberry.  If not, see <http://www.gnu.org/licenses/>.
-*/
+/*
+ * Strawberry Music Player
+ * This file was part of Clementine
+ * Copyright 2017-2018, Jonas Kvinge <jonas@jkvinge.net>
+ *
+ * Strawberry is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * Strawberry is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with Strawberry.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
 
 #ifndef PHONONENGINE_H
 #define PHONONENGINE_H
@@ -39,6 +43,8 @@ class PhononEngine : public Engine::Base {
   ~PhononEngine();
 
   bool Init();
+  
+  OutputDetailsList GetOutputsList() const;
 
   bool CanDecode(const QUrl &url);
 
@@ -56,6 +62,9 @@ class PhononEngine : public Engine::Base {
 
   qint64 position_nanosec() const;
   qint64 length_nanosec() const;
+  
+  QString DefaultOutput() { return ""; }
+  bool CustomDeviceSupport(const QString &name);
 
  protected:
   void SetVolumeSW( uint percent );