ontology now accepts viri as a frame.

Ontologies are specified by IRI and version IRI. Previously
it was impossible to specify this as it must be set at
construction time.
render can now cope with ontology form.

This required a few changes to the ontology functionality also
in particular enabling the use with IRI or strings. render-sio
tests have been updated to use this functionality as well which
adds a new test and removes some cruft.