Made optimizations to connector plugin, fixed issue 670 and possibly issue 664

git-svn-id: http://svg-edit.googlecode.com/svn/trunk@1714 eee81c28-f429-11dd-99c0-75d572ba1ddd

editor/svgicons/jquery.svgicons.js

@@ -500,7 +500,7 @@ $(function() {
 	
 	$.getSvgIcon = function(id, uniqueClone) { 
 		var icon = svg_icons[id];
-		if(uniqueClone) {
+		if(uniqueClone && icon) {
 			icon = fixIDs(icon, 0, true).clone(true);
 		}
 		return icon;