Moving the perl5120delta warnings about \N{...} into perlre

While writing about \N for the next Llama, I discovered some warnings
about \N{...} in perl5120delta.pod that were not in perlre.pod. In the
branch briandfoy/slashN, I've fixed that in commit 434a17. 

I'm not sure if there are other things that should have gone into the
warnings about \N{...} in perlre because I haven't followed all of the
discussions about it. Someone should check my work.

If people like the patch, merge it into blead. I also think this would
be good to cherrypick into the next 5.12 release.

-- 
brian d foy <brian.d.foy@gmail.com>

• Moving the perl5120delta warnings about \N{...} into perlre by brian d foy
• Re: Moving the perl5120delta warnings about \N{...} into perlre by Karl Williamson