Remove 'use UNIVERSAL;', switch to UNIVERSAL::isa()

Remove 'use UNIVERSAL;', switch to UNIVERSAL::isa()

Subject: Re: UNIVERSAL.pm and import methods

I wrote
> I've a sneaking feeling that I'm the only person who's tried to use
> this.    And as you might guess from my bug reports, I've learnt the
> error of my ways.

I spoke too soon.   There are three uses in the standard distribution.
The attached patch should get rid of them.

Probably worth doing this irrespective of how the UNIVERSAL/import
question is resolved.

p5p-msgid: E0whaZJ-0007BA-00@ursa.cus.cam.ac.uk