TODO:

* Complete OWL2RL support
* Create an RDFS + OWL2RL engine, or maybe a generic composite engine
* Create an OWL Extras engine

I don't plan on writing the following myself but would accept patches for:

* Manchester syntax parser
* OWL/XML parser
* OwlFn, Manchester, OWL/XML serialisers
	- OwlFn serialiser is now in OWL::DirectSemantics.

Ideas for separate packages:

* OWL API
* Wrappers for external reasoning tools
* A log:implies engine and perhaps some other parts of Notation 3 logic.

