Resolves issue #23.

Adds audio output display and management options supporting mono and 
stereo output options.

Provides audio output supporting prioritization by talkgroup and/or 
channel selection.

Supports muting all channels, or muting individual channels and
individual audio gain/volume controls.

src/audio/AudioEvent.java

@@ -23,8 +23,13 @@ public class AudioEvent
 
 	public enum Type
 	{
+		AUDIO_MUTED,
+		AUDIO_UNMUTED,
+		AUDIO_SQUELCHED,
+		AUDIO_UNSQUELCHED,
 		AUDIO_STARTED,
 		AUDIO_STOPPED,
-		AUDIO_CONFIGURATION_CHANGED;
+		AUDIO_CONFIGURATION_CHANGE_STARTED,
+		AUDIO_CONFIGURATION_CHANGE_COMPLETE;
 	}
 }