XXX choices described here to be reviewed.

The namespace here is a subset of <http://www.iana.org/assignments/character-sets>, using the "preferred MIME name" where such exists, as this seems to be the most commonly used namespace for encodings.

For looking up namespaces using any of their aliases and case-insensitively, use <import:org.cubik.cle.io.charsets> (XXX bad name)