https://developers.google.com/maps/tutorials/
https://developers.google.com/maps/documentation/javascript/datalayer
https://developers.google.com/kml/documentation/kmlreference
https://developers.google.com/kml/documentation/kml_tut
https://developers.google.com/maps/documentation/javascript/reference
https://developers.google.com/maps/documentation/javascript/3.exp/reference#Polygon
https://developers.google.com/maps/documentation/javascript/examples/polygon-simple
https://developers.google.com/maps/documentation/javascript/datalayer
https://developers.google.com/maps/documentation/javascript/examples/layer-data-dragndrop
http://stackoverflow.com/questions/23071775/how-to-remove-data-from-gmap