give an "id" attribute (beside the "name") in the <map> tab

some browsers (Chrome, FF, Opera) in some versions require that ( see http://stackoverflow.com/questions/5527290/image-map-support-in-firefox-chrome-and-other-browsers , http://stackoverflow.com/questions/11156054/image-map-not-referenceable-by-id  etc...)
Merge pull request #2 from farialima/master

give an "id" attribute (beside the "name") in the <map> tab