private static boolean isAndFilter(final IGeocacheFilter filter) {
        return filter instanceof AndGeocacheFilter && !(filter instanceof NotGeocacheFilter);
    }
Extracts quickfilter settings from this filter. For each quickfilter, an entry is returned
For each quickfilter, it is stored whether corresponding caches shall be shown (true) or not (false)
main/src/main/java/cgeo/geocaching/filters/core/GeocacheFilter.java