Changed variable rendering in Manchester OWL Syntax to preserve ns.

Variables like <urn:swrl#x> are rendered as ?x.
Strings like ?x are parsed as <urn:swrl#x>

Variables like <foo#x> are rendered as ?<foo#x>.
Strings like ?<foo#x> are parsed as <foo#x>.

This allows for parsing of simple forms and preserves namespaces in
roundtripping if a different namespace is used.