Clear undo history when clearing document

git-svn-id: http://svg-edit.googlecode.com/svn/trunk@252 eee81c28-f429-11dd-99c0-75d572ba1ddd

editor/svg-editor.js

@@ -345,8 +345,9 @@ function svg_edit_setup() {
 	}
 
 	var clickClear = function(){
-		if( confirm('Do you want to clear the drawing?') ) {
+		if( confirm('Do you want to clear the drawing?\nThis will also erase your undo history!') ) {
 			svgCanvas.clear();
+			updateContextPanel();
 		}
 	}