add white background to image for visibility on black background in mapview

git-svn-id: http://svn.openstreetmap.org/applications/share/map-icons@30870 b9d5c4c9-76e1-0310-9c85-f3177eceb1e4
delete icon. was replaced by crossing_ref_zebra.svg

git-svn-id: http://svn.openstreetmap.org/applications/share/map-icons@30871 b9d5c4c9-76e1-0310-9c85-f3177eceb1e4