Refs #140 , refs #85 Rename namespace voice to audio.

In #85 the voice context will be renamed to audio context, so the CValueObject classes will be renamed to namespace Audio too.
As #140 changes many CValueClasses, this crossover change is done in the same unit of work.

src/blackmisc/blackmiscfreefunctions.h

@@ -87,10 +87,10 @@ namespace BlackMisc
         void registerMetadata();
     }
 
-    namespace Voice
+    namespace Audio
     {
         /*!
-         * \brief Register metadata for voice
+         * \brief Register metadata for audio / voice
          */
         void registerMetadata();
     }