message: Update psd_len calculation in get_psd_welch
diff: @@ -257,7 +257,7 @@ std::pair<double *, double *> DataFilter::get_psd_welch (
  delete[] freq;
  throw BrainFlowException ("failed to get_psd_welch", res);
  }
  - *psd_len = data_len / 2 + 1;
  + *psd_len = nfft / 2 + 1;
  return std::make_pair (ampl, freq);
  }
  