identifynn: drop extend_dataset_by_frame_augmen...
identifynn: drop extend_dataset_by_frame_augmen...

This doesn't seem necessary now that we have the 'extra_stem'
namespacing; i.e. there's no longer a need to simulate what data looks
like when it's been automarked, because we can happily have it live in
parallel to manually-marked data.

aevri/mel,aevri/mel