Vectorise owlsome, only. not, atleast, exactly updated to cope.

owlsome and only can now work cleanly when given multiple arguments.
They always return a list as a result. not, atleast, exactly now take a single
arg or a list or length 1.
General introduction to OWL/SW added.
Most functions now provide a pure option. Includes breaking changes.

Instead of using the current ontology, most functions can now take an ontology
as the first argument, which makes them (sort of) pure assuming that they
don't change the ontology itself. Most functions now "broadcast" as well.

Where possible this is backward compatible. However, some return types have
changed, to returning lists rather than single entities. And a few functions
which took an ontology argument not as the first argument will have broken.
as-disjoint-subclasses was incorrectly leaving a :disjoint keyword in the
evaluated body. Probably benign, but it increases the complexity of macro
expansion.
Added pure option to subclasses and added superclasses function.