ref: reorganize exports into core/extras

src/index.ts

@@ -1,14 +1,20 @@
-import { QWeb } from "./qweb";
-import { EventBus } from "./event_bus";
 import { Component, PureComponent } from "./component";
-import { Store, connect } from "./store";
+import { EventBus } from "./event_bus";
+import { QWeb } from "./qweb";
+import { Registry } from "./registry";
+import { connect, Store } from "./store";
 import * as utils from "./utils";
+
 export const core = {
   QWeb,
   EventBus,
   Component,
   PureComponent,
-  Store,
-  connect,
   utils
 };
+
+export const extras = {
+  Store,
+  connect,
+  Registry
+};