Add Wikidata metadata

[andrewtavis]

One way to provide more data for wikirec would be to add metadata for the given article via its Wikidata:Main_Page page. This would change the manner in which the data is extracted, but article texts could be derived as well via the Wikipedia pages that are linked to the Wikidata entity. Whether or not the project should be shifted to focus on Wikidata as a main data source could also be discussed, with tools like WikidataIntegrator being used to derive article categories and query the needed information.