acdh-oeaw/histogis-data: new data + wiki data ids

We added new data and enhanced and harmonized existing data. Our data base now contains data on: State borders of German states, 1815 – 1870 State borders of the German Empire, 1871 - 1919 State borders of the Austrian / Austro-Hungarian Empire, 1815 - 1918 State borders of other European nations, 1815 – 1919 Borders of the Austrian / Austro-Hungarian crownlands, 1815 – 1918 Geometries, names and dates have been harmonized across all data sets, and Wikidata IDs have been added to (almost) all features