A link check of every manifest found 404 licence or provider pages for
OpenSeaMap seamarks, EMODnet bathymetry and the PDOK, basemap.at, Geneva
SITG, ICGC Catalunya, Luxembourg and Vlaanderen aerial photos, and no
answer from the SEDAC GPW, Minnesota and Bangor hosts. Drop those 11
entries, renumber the unpublished share-token ledger, point the tests at
remaining entries and regenerate DATA_SOURCES.md.