Add hyperlinks for Wikidata entries

This will hopefully convert Wikidata tags into hyperlinks to wikidata.org.

For example, It should map the OSM tag 'wikidata=Q19777' to 'https://www.wikidata.org/wiki/Q19777', this could be seen [here](http://overpass-turbo.eu/s/2Hl)

I don't speak javascript, I just adapted the code to generate Wikipedia links and I haven't tested this, so please excuse me if I'm way off.