[vector] Removal of some operations

[John Rose]

On Feb 2, 2018, at 1:18 AM, Paul Sandoz <paul.sandoz at oracle.com> wrote:
> 
> In an effort to shrink down the API to a smaller set of operations and thus make it easier scope out a first viable implementation we can remove the following lesser known operations:

Rather than complete removal, I think it would be better to
sideline those operations into a separate class, as static
generic algorithms.

Maybe the *Exact guys could go into one class.  And
eventually a set of *Saturating algorithms, alongside it.

(Also, does it really say "substract"?)

— John