aggregates in reactor: deleting 2 or more values when using Stardog fails

[mathib]

When I use the propertyReactor in 'aggregate' mode with the aggregate viewer and editor, I get the option to select multiple values that can be deleted. Whenever I select 2 or more and want to delete them, I get an error from my Stardog db, because the query send by LD-R contains two DELETE-WHERE clauses, which is not allowed by Stardog (but is accepted in the case of Virtuoso). LD-R should look to the dataset 'endpoint' setting in the server.js config and treat the query different in the case of a Stardog enpoint. Alternatively, the SPARQL delete query can also be combined in one DELETE-WHERE query, that is acceptable for every type of endpoint.