clarify distinction between delete my map and delete revision

[CH4Code]

1. Would be good if "delete my map" was actually called "delete this revision" of the map so noone has to sweat heavily every time before clicking that button out of anxiety that the whole map and all its revisions will vanish.
2. An option to "delete all revisions" of a map with one click. (some maps have more than 28 revisions, deleting one by one is painstakingly repetitive)