uk coordinates
improve uk coordinates in 1940 as well

Commit fe01834 (uk coordinates) improved UK coordinates for 1939 only.
Apply it to 1940.
pass the marker object to addMarker()

move the marker intelligence from updateMarkers() to addMarker().
updateMarkers() doesn't need to know any details about the marker
object so just pass it to addMaker() and let it do whatever it needs
to add the marker.