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/pulsedevicefinder.cpp

@@ -34,7 +34,7 @@
 #include "devicefinder.h"
 #include "pulsedevicefinder.h"
 
-PulseDeviceFinder::PulseDeviceFinder() : DeviceFinder("pulseaudio", "pulsesink"), mainloop_(nullptr), context_(nullptr) {
+PulseDeviceFinder::PulseDeviceFinder() : DeviceFinder("pulseaudio", {"pulseaudio", "pulse", "pulsesink"} ), mainloop_(nullptr), context_(nullptr) {
 }
 
 bool PulseDeviceFinder::Initialise() {