Persisting HQDM Objects

[twalmsley]

As part the recent development work, HQDM was decoupled from RDF and there is now no easy way to convert Things to the RDF triples needed for persisting an object to an RDF triple store - clients have to call MagmaCoreService.create(Thing) for each thing, or create a batch update manually using the DbTransformation classes.

Ideally there would be a service call that would take a collection of Thing objects and convert them to the required DbTransformation which can then be applied using the MagmaCoreService (a convenience function to convert and apply can also be provided, but there are cases where the conversion result is needed for other purposes so there should be a way to create a DbTransformation without also applying.)

This would allow clients to persist Things directly rather than using the indirect routes currently available.

[twalmsley]

Released in 2.1.0