replace internal module to namespace

d3/plugins/d3.superformula.d.ts

@@ -1,9 +1,9 @@
 /// <reference path="../d3.d.ts" />
 
-declare module d3 {
+declare namespace d3 {
     export function superformula<T>(): Superformula<T>;
 
-    module superformula {
+    namespace superformula {
         interface Type {
             m: number;
             n1: number;