provide a way to sync between visualization and sound

workaround for http://musicpd.org/mantis/view.php?id=2503

src/visualizer.h

@@ -65,6 +65,9 @@ class Visualizer : public Screen<Window>
 		void DrawFrequencySpectrum(int16_t *, ssize_t);
 #		endif // HAVE_FFTW3_H
 		
+		int itsOutputID;
+		timeval itsTimer;
+		
 		int itsFifo;
 #		ifdef HAVE_FFTW3_H
 		unsigned *itsFreqsMagnitude;