improved __dir__ for entityTypes. validationPlugin no longer returns an object, instead, the get_validationPlugin() should be used

handling of boolean attributes in update of entity types. Bugfix of validationPlugin when updating entity types

creation of property types for controlled vocabulary and materialTypes now work

bugfix when vocabulary attribute was not identical to the code of the aassigned property type

bugfix: get vocabulary from property_type.vocabulary attribute, not from code of assigned properties

fixed get_property_assignments() method for dataSet-, experiment- and materialTypes

fixed bug when searching for dataSets and experiments of a given type