feat: renderable events

packages/graphics/renderable.js

@@ -1,6 +1,14 @@
-export class Renderable {
+import {compose} from '@avocado/core';
+import {EventEmitter} from '@avocado/mixins';
+
+const decorate = compose(
+  EventEmitter,
+);
+
+export class Renderable extends decorate(class {}) {
 
   constructor() {
+    super();
     this.parent = null;
     this._zIndex = 0;
   }