- l10n: Add Chinese (simplified) extension locales (Thanks, @enlove!)

- Linting (ESLint): Avoid reporting `no-console`
- Refactoring: Avoid Firefox console errors with hidden iframe
- Docs (CHANGES): Fix Markdown heading level

editor/extensions/ext-locale/shapes/zh-CN.js

@@ -0,0 +1,24 @@
+export default {
+  loading: '正在加载...',
+  categories: {
+    basic: '基本',
+    object: '对象',
+    symbol: '符号',
+    arrow: '箭头',
+    flowchart: '工作流',
+    animal: '动物',
+    game: '棋牌',
+    dialog_balloon: '会话框',
+    electronics: '电子',
+    math: '数学',
+    music: '音乐',
+    misc: '其他',
+    raphael_1: 'raphaeljs.com 集合 1',
+    raphael_2: 'raphaeljs.com 集合 2'
+  },
+  buttons: [
+    {
+      title: '图元库'
+    }
+  ]
+};