Handle nesting better in the clone method so that we don't wipe out the line defaults when the scatter chart extends

src/core/core.js

@@ -108,8 +108,12 @@
             var objClone = {};
             each(obj, function(value, key) {
                 if (obj.hasOwnProperty(key)) {
+                    if (typeof value === 'object' && value !== null) {
+                        objClone[key] = clone(value);
+                    } else {
                         objClone[key] = value;
                     }
+                }
             });
             return objClone;
         },