spectrogram.from_timeseries: fix nproc bug

   - don't allow more processes than spectrogram time steps
   - that does not make sense
   - this is Chewbacca...
TimeSeries.append: bug fix in resize=True
Spectrogram.is_compatible: better error statements
spectrogram.from_timeseries: fixed nsteps < nproc
TimeSeries.resample: use scipy decimate instead

    - added TimeSeriesDict.resample for group resampling
TimeSeriesDict.resample: remove print statement
TimeSeriesDict.read: resample in bulk

    - resampling individually leaves a lot of zeros, which are bad.
frameCPP: rejigged cropping and resampling