Improvments to gstreamer backend and settings +++

- Fixed bug not setting environment for gstreamer before initialization
- Fixed windows directsound device
- Fixed crash on failure to create gstreamer element
- Fixed crash when switching backend
- Don't stop playback if equalizer or replay gain fails in gstreamer
- Improvments to backend settings
- Fixed backend settings to work for windows
- Fixed replay gain settings not working
- Fixed right click menu for album showing in statusview even when no song was playing
- Removed redundant code

src/engine/osxdevicefinder.cpp

@@ -101,8 +101,8 @@ QList<DeviceFinder::Device> OsxDeviceFinder::ListDevices() {
 
     Device dev;
     dev.description = QString::fromUtf8(CFStringGetCStringPtr(*device_name, CFStringGetSystemEncoding()));
-    dev.device_property_value = id;
-    dev.icon_name = GuessIconName(dev.description);
+    dev.value = id;
+    dev.iconname = GuessIconName(dev.description);
     ret.append(dev);
   }
   return ret;