[new feature] add i18n support (#310)

* fix: Tabbar icon line-height

* [new feature] progress add showPivot prop

* [new feature] TabItem support vue-router

* [new feature] update document header style

* [Doc] add toast english ducoment

* [new feature] add i18n support

* feat: Extract demos from markdown

* feat: Base components demos

* [new feature] complete demo extract & translate

* [fix] text cases

* fix: add deepAssign test cases

* fix: changelog detail

* [new feature] AddressEdit support i18n

docs/markdown/zh-CN/number-keyboard.md

@@ -0,0 +1,69 @@
+## NumberKeyboard 数字键盘
+
+### 使用指南
+``` javascript
+import { NumberKeyboard } from 'vant';
+
+Vue.component(NumberKeyboard.name, NumberKeyboard);
+```
+
+### 代码演示
+
+#### 基础用法
+
+```html
+<van-button @touchstart.native.stop="showKeyboard = true">
+  弹出键盘
+</van-button>
+
+<van-button @touchstart.native.stop="showKeyboard = false">
+  收起键盘
+</van-button>
+
+<van-number-keyboard
+  :show="showKeyboard"
+  @blur="showKeyboard = false"
+  @input="onInput"
+  @delete="onDelete"
+/>
+```
+
+```javascript
+export default {
+  data() {
+    return {
+      showKeyboard: true
+    }
+  },
+
+  methods: {
+    onInput(value) {
+      Toast(value);
+    },
+    onDelete() {
+      Toast('delete');
+    }
+  }
+}
+```
+
+### API
+
+| 参数 | 说明 | 类型 | 默认值 | 可选值 |
+|-----------|-----------|-----------|-------------|-------------|
+| show | 是否显示键盘 | `Boolean` | - | - |
+| title | 键盘标题 | `String` | - | - |
+| extraKey | 左下角按键内容 | `String` | `''` | - |
+| zIndex | 键盘 z-index | `Number` | `100` | - |
+| transition | 是否开启过场动画 | `Boolean` | `true` | - |
+| showDeleteKey | 是否展示删除按钮 | `Boolean` | `true` | - |
+
+### Event
+
+| 事件名 | 说明 | 参数 |
+|-----------|-----------|-----------|
+| input | 点击按键时触发 | key: 按键内容 |
+| delete | 点击删除键时触发 | - |
+| blur | 点击非键盘区域时触发 | - |
+| show | 键盘完全弹出时触发 | - |
+| hide | 键盘完全收起时触发 | - |