Changes
Renamed average_and_group to group; averaging is disabled/enabled based on the value of win_len: disabled if win_len=1, enabled if win_len>1
Added method process(audio_loader, model, ...) that delegates to process_audio_loader (nice to have shorter method names)
Changed default settings to buffer=0 (no buffer), win_len=1 (no averaging) and group=False (no grouping).
Argument step no longer required by process_audio_loader. The step size is automatically inferred from difference between consecutive spectrogram offsets.
Added optional progress bar
group_detections accepts batches composed of spectrograms from multiple files
