std::vector for wave track pointers; remove deprecated TrackList function; ...

... and some more uses of const

src/Mix.h

@@ -22,6 +22,7 @@ class TimeTrack;
 class TrackFactory;
 class TrackList;
 class WaveTrack;
+class WaveTrackConstArray;
 
 /** @brief Mixes together all input tracks, applying any envelopes, amplitude
  * gain, panning, and real-time effects in the process.
@@ -74,7 +75,7 @@ class AUDACITY_DLL_API Mixer {
     class WarpOptions
     {
     public:
-       explicit WarpOptions(TimeTrack *t)
+       explicit WarpOptions(const TimeTrack *t)
           : timeTrack(t), minSpeed(0.0), maxSpeed(0.0)
        {}
 
@@ -82,7 +83,7 @@ class AUDACITY_DLL_API Mixer {
 
     private:
        friend class Mixer;
-       TimeTrack *timeTrack;
+       const TimeTrack *timeTrack;
        double minSpeed, maxSpeed;
     };
 
@@ -90,7 +91,7 @@ class AUDACITY_DLL_API Mixer {
    // Constructor / Destructor
    //
 
-   Mixer(int numInputTracks, WaveTrack **inputTracks,
+   Mixer(const WaveTrackConstArray &inputTracks,
          const WarpOptions &warpOptions,
          double startTime, double stopTime,
          int numOutChannels, int outBufferSize, bool outInterleaved,
@@ -139,10 +140,10 @@ class AUDACITY_DLL_API Mixer {
  private:
 
    void Clear();
-   sampleCount MixSameRate(int *channelFlags, WaveTrack *src,
+   sampleCount MixSameRate(int *channelFlags, const WaveTrack *src,
                            sampleCount *pos);
 
-   sampleCount MixVariableRates(int *channelFlags, WaveTrack *track,
+   sampleCount MixVariableRates(int *channelFlags, const WaveTrack *track,
                                 sampleCount *pos, float *queue,
                                 int *queueStart, int *queueLen,
                                 Resample * pResample);
@@ -150,9 +151,9 @@ class AUDACITY_DLL_API Mixer {
  private:
    // Input
    int              mNumInputTracks;
-   WaveTrack      **mInputTrack;
+   const WaveTrack **mInputTrack;
    bool             mbVariableRates;
-   TimeTrack       *mTimeTrack;
+   const TimeTrack *mTimeTrack;
    sampleCount     *mSamplePos;
    bool             mApplyTrackGains;
    float           *mGains;