Support :righthandtraffic pseudo class

As soon as #8 has been implemented, we can use external data to check where the current object is located and if there's left/right hand traffic. We can convert the left/right hand traffic data from JOSM to a CSV file (with `ogr2ogr -lco GEOMETRY=AS_WKT --config OSM_USE_CUSTOM_INDEXING NO -f CSV left-right-hand-traffic.csv left-right-hand-traffic.osm`).

JOSM left/right data: http://josm.openstreetmap.de/browser/josm/trunk/data/left-right-hand-traffic.osm