map.js: refactor default overlays creation
map.js: refactor default overlays creation

McBen/ingress-intel-total-conversion,McBen/ingress-intel-total-conversion,sndirsch/ingress-intel-total-conversion,McBen/ingress-intel-total-conversion,McBen/ingress-intel-total-conversion,sndirsch/ingress-intel-total-conversion,sndirsch/ingress-intel-total-conversion,sndirsch/ingress-intel-total-conversion,McBen/ingress-intel-total-conversion,sndirsch/ingress-intel-total-conversion