[m-rev.] for review: Deprecate array least_index/greatest_index functions and add replacements.

[Julien Fischer]

On Fri, 6 Apr 2018, Peter Wang wrote:

> As suggested by Julien a few months back.
>
> library/array.m:
>    Add det_least_index, semidet_least_index, det_greatest_index,
>    semidet_greatest_index functions.
>
>    Deprecate least_index, greatest_index with the intention of making
>    them semidet eventually.

That's fine.

Julien.