Added WikidataQuery page generator

The generator takes a WikidataQuery string and works on the resulting
page set. This allows complex queries like "Places in the U.S. that are
named after Francis of Assisi":
-wikidataquery:tree[30][150][17,131] AND claim[138:676555]

Change-Id: If35fbc947889dc4d7a6afcebedd899d5e1ae54db
Merge "Added WikidataQuery page generator"