[BioPython] numpy migration for Bio.PDB.Vector

[Peter]

>> As to the code, I've only skimmed over it.  One thing that caught my
>> eye is you are using scipy, which we currently do not want to
>> introduce as a Biopython dependency.
>
> Alright, this was only a shortcut to get the determinant. Actually there
> is no need to use scipy.

Good - that's what I would have assumed anyway.

>> If you have any views on this migration, please voice them
>> (ideally on that thread).
>
> No, nothing to add to things already written.

OK, good :)

Peter