https://developers.google.com/kml/documentation/kml_tut
https://developers.google.com/maps/documentation/javascript/examples/layer-kml?hl=zh-cnhttps://developers.google.com/maps/tutorials/kml/https://developers.google.com/maps/support/kmlmapshttps://developers.google.com/kml/documentation/
https://www.youtube.com/watch?v=_AZSZvOc0fghttp://display-kml.appspot.com/
http://www.opengeospatial.org/standards/kml
http://www.instructables.com/id/Creating-KML-Files-For-Your-Custom-Google-Maps/
http://stackoverflow.com/questions/10736664/load-kml-file-into-google-maps-api