Support testing output against the OWL API

[phillord]

We currently test whether we can read the OWL API output, as all the test files from bubo are producing using it.

But there is nothing that will test whether the OWL API can read horned-owl files.

We can achieve this by producing something by converting form the XML file into various outputs. Then write a small tool in bubo to produce output easily comparable to horned-summary,