John (Thales) code to make the waveform display look like the output of the gain and pan sliders, rather than the input. Added as EXPERIMENTAL_OUTPUT_DISPLAY since there is work to do, but I think this deserves wider input/views.

src/TrackPanel.h

@@ -497,6 +497,9 @@ protected:
    virtual int IdOfRate( int rate );
    virtual int IdOfFormat( int format );
 
+#ifdef EXPERIMENTAL_OUTPUT_DISPLAY
+   void UpdateVirtualStereoOrder();
+#endif
    // Accessors...
    virtual bool HasSoloButton(){  return mSoloPref!=wxT("None");};