Merge remote-tracking branch 'remotes/xdarkice/gstreamer' into develop

Conflicts:
	VocaluxeLib/Menu/SongMenu/CSongMenuFramework.cs

Set GStreamer as default audio decoder

VocaluxeLib/Menu/IMenu.cs

@@ -637,7 +637,8 @@ namespace Vocaluxe.Menu
     public enum EPlaybackLib
     {
         PortAudio,
-        OpenAL
+        OpenAL,
+        Gstreamer
     }
 
     public enum EWebcamLib
@@ -656,7 +657,8 @@ namespace Vocaluxe.Menu
 
     public enum EVideoDecoder
     {
-        FFmpeg
+        FFmpeg,
+        Gstreamer
     }
 
     public enum ESongMenu