Integrate perlio:

[  9096]
EBCDIC sanity - phase I
- rename utf8/uv functions to indicate what sort of uv they provide (uvuni/uvchr)
- use utf8n_xxxx (c.f. pvn) for forms which take length.
- back out vN.N and $^V exceptions to e2a/a2e
- make "locale" isxxx macros be uvchr (may be redundant?)
Not clear yet that toUPPER_uni et. al. return being handled correctly.
The tr// and rexexp stuff still needs an audit, assumption is they are working
in Unicode space.
Need to provide v5.6 names for XS modules (decide is uni or chr ?).

p4raw-link: @9096 on //depot/perlio: 9041c2e396c8c7de7680a2007dc341a9f65be0d0

p4raw-id: //depot/perl@9097