trying to remove the "shape"literals from the shex and orient closer on the original dcat schema

I tried to get the visualization a little bit easier to understand by getting rid of e.g. dcat:Dataset and an additional DatasetShape and I think it works that way. We could consider removing all definitions of rdfs:subClassOf from the shape expressions, as this is something that we define in the ontology (where necessary).

Also note that now the script in PyShEx.ipynb fails because of the definition dct:publisher @n4e:Organization * ; -> the graph per resource only contains the IRI to the organization, so we would need to additionally fetch this and merge into the local graph before the validation.

@ralf.klammer please check if this merge would go into the right direction from your perspective