Allow long tones to be generated (> 2^31)

src/effects/ToneGen.cpp

@@ -127,7 +127,7 @@ bool EffectToneGen::TransferParameters( Shuttle & shuttle )
 bool EffectToneGen::MakeTone(float *buffer, sampleCount len)
 {
    double throwaway = 0;        //passed to modf but never used
-   int i;
+   sampleCount i;
    double f = 0.0;
 
    double BlendedFrequency;

src/effects/ToneGen.h

@@ -85,7 +85,7 @@ class EffectToneGen : public BlockGenerator {
 
    // mSample is an external placeholder to remember the last "buffer"
    // position so we use it to reinitialize from where we left
-   int mSample;
+   sampleCount mSample;
  // friendship ...
  friend class ToneGenDialog;