Add API method to enable audio loopback in IVoice and

audio context

refs #136

src/blackcore/context_audio_proxy.h

@@ -110,6 +110,9 @@ namespace BlackCore
 
         //! \copydoc IContextAudio::getSquelchValue()
         virtual double getSquelchValue() const override;
+
+        //! \copydoc IContextAudio::enableAudioLoopback()
+        virtual void enableAudioLoopback(bool enable = true) override;
     };
 }