Consider alignment with Data Provider Node ontology

[clange]

The Data Provider Node ontology (see also these slides and this paper) seems to cover a subset of the IDS infomodel and is also aligned with DCAT. It's not a standard, but reasonably well done (e.g., meeting the LOV requirements), and we are not (yet) a standard either ;-) Thus, it might make sense to look at it (with a low priority) and probably align the IDS infomodel with it.