fix a bug in svgToString function:

some elements have no attribute, so when convert it to stinrg some namespace can't be set correctly.

now, the tag like this can be correctly converted:
<se:mytag>hello</se:mytag>

git-svn-id: http://svg-edit.googlecode.com/svn/trunk@2517 eee81c28-f429-11dd-99c0-75d572ba1ddd

editor/svgcanvas.js

@@ -4120,6 +4120,13 @@ this.svgToString = function(elem, indent) {
 			// Check elements for namespaces, add if found
 			$(elem).find('*').andSelf().each(function() {
 				var el = this;
+        // for some elements have no attribute
+        var uri = this.namespaceURI;
+        if(uri && !nsuris[uri] && nsMap[uri] && nsMap[uri] !== 'xmlns' && nsMap[uri] !== 'xml' ) {
+          nsuris[uri] = true;
+          out.push(" xmlns:" + nsMap[uri] + '="' + uri +'"');
+        }
+        
 				$.each(this.attributes, function(i, attr) {
 					var uri = attr.namespaceURI;
 					if (uri && !nsuris[uri] && nsMap[uri] !== 'xmlns' && nsMap[uri] !== 'xml' ) {