Paul Licameli's Spectral Editing Patch.

This relies on three new nyquist scripts to actually do the editing.  The peak-snapping code in FrequencyWindow has been extracted into a new class, SpectrumAnalyst, to provide peak-snapping in spectrogram too.

src/WaveTrack.h

@@ -401,7 +401,7 @@ class AUDACITY_DLL_API WaveTrack: public Track {
          mLastDisplay=mDisplay;    // remember last display mode for wave and wavedb so they can remap
       mDisplay = display;
    }
-   int GetDisplay() {return mDisplay;}
+   int GetDisplay() const {return mDisplay;}
    int GetLastDisplay() {return mLastDisplay;}
 
    void GetDisplayBounds(float *min, float *max);