speed up method fetching of lexical information from the KB

[mromanello]

(the same applies to properties KnowledgeBase.author_abbreviations, .work_titles etc.)

in order to be able to parallelize the generation of counts, a method is needed that gets all CTS URNs from the KB. The SPARQL query would be:

PREFIX frbroo: <http://erlangen-crm.org/efrbroo/>
            PREFIX crm: <http://erlangen-crm.org/current/>
            PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>
            SELECT ?label ?resource_URI ?resource_type
            WHERE {
                ?resource_URI rdf:type ?resource_type .
                ?resource_URI crm:P1_is_identified_by ?urn .
                ?urn a crm:E42_Identifier .
                ?urn rdfs:label ?label
            }
            LIMIT 10