Update to ndarray-0.12 (from ndarray-0.10)

[hegza]

• Update dependency ndarray from 0.10.11 to 0.12.1.
• Change Slice op inner type from ndarray-0.10 Si to respective ndarray-0.12 Slice.
• Wrap Slice into SliceInfo in calls to slice*()
  • A maintainer of ndarray (jturner314) recommends that slicing be done with s![] where applicable. I don't think it is applicable in this use case and I decided to do that wrapping instead.
• In examples: cast sliced, constant sized batches into dynamic ndarrays with .into_dyn(), as the new ndarray-0.12 API seems to require that.

[raskr]

Appreciate your work👍 (to tell the truth, I had failed to upgrade ndarray because there was nothing equivalent to Slice type previously...