various: encapsulate all code in the olive namespace to avoid name collisions

Large-scale code cleanup. Also adds a license to the top of all files that were
missing it.

app/audio/outputmanager.h

@@ -29,6 +29,8 @@
 
 #include "outputdeviceproxy.h"
 
+OLIVE_NAMESPACE_ENTER
+
 class AudioOutputManager : public QObject
 {
   Q_OBJECT
@@ -88,4 +90,6 @@ private slots:
   void PushMoreSamples();
 };
 
+OLIVE_NAMESPACE_EXIT
+
 #endif // AUDIOHYBRIDDEVICE_H