Added a popularity filter that allows to filter out caches that have more  then a predefined number of favorite points

The filter allows to filter caches with more than 10,20,50,100,200, and 500 favorite points.

BTW: I would recommend to rename the German translation of Popularity from "Beliebtheit" to "Favoriten" since this makes the filters and sorts much more intuitive to use for a German cacher. I have not changed anything because I guess that such an HMI change would require a formal request in some forum. So my ask is: where can I request it?