the References section of rdf:PlainLiteral

The References section was not using the wiki templates for references.
I fixed that, adding these reference templates:

    * References/ref-iso-iec-10646
    * References/ref-rfc-4647
    * References/ref-unicode
    * References/ref-xpath-func
    * References/ref-xpath20

(I just copied from from what we had.  Some of them (eg xpath20) don't
actually follow W3C guidelines, but I'm out of time to work on this.)

I then alphabetized them.  The HTML diff (before alphabetization) is
attached (since the wiki diff is useless when it's about templates).

     -- Sandro