classification plugin should be general, so also for non-glTF files and also from glTF files with IFC identifiers

[JWerbrouck]

classification plugin should be general, so also for non-glTF files and also from glTF files with IFC identifiers. At the moment, it only looks for the relationship:

?parent omg:hasGeometry/fog:hasGltfId ?guid .

and then for rdf:types of the parent element. In the IFC-to-glTF conversion, however, the link is established using:

?parent props:globalIdIfcRoot/schema:value ?guid .