XMLLiteral in SPARQL Results XML format

The SPARQL Results XML Format spec is silent regarding XMLLiteral
datatypes, but the schemas specify that only "text" is allowed in an
srx:literal element. This means that XMLLiteral values must have XML
markup replaced with character entities, or enclosed in a CDATA section.

This is roadblock to fluent processing of RDF data that includes
XMLLiteral values.

Consider for the next revision to specify that XMLLiteral values be
emitted as XML in a non-srx namespace.

The attached patch to the rnc schema (available at
http://www.w3.org/2005/sparql-results) enforces that srx:literal
elements with datatype rdf:XMLLiteral must have element children from a
non-srx namespace.

(The patch also fixes the res: namespace in the schema, which does not
match the namespace URI given in the spec.)

Regards,
--Paul