[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/en-US/swipe.md

@@ -0,0 +1,62 @@
+## Swipe
+
+### Install
+``` javascript
+import { Swipe, SwipeItem } from 'vant';
+
+Vue.component(Swipe.name, Swipe);
+Vue.component(SwipeItem.name, SwipeItem);
+```
+
+### Usage
+
+#### Basic Usage
+Use `autoplay` prop to set autoplay interval
+
+```html
+<van-swipe :autoplay="3000">
+  <van-swipe-item>1</van-swipe-item>
+  <van-swipe-item>2</van-swipe-item>
+  <van-swipe-item>3</van-swipe-item>
+  <van-swipe-item>4</van-swipe-item>
+</van-swipe>
+```
+
+#### Image Lazyload
+Use [Lazyload](#/zh-CN/component/lazyload) component to lazyload image
+
+```html
+<van-swipe>
+  <van-swipe-item v-for="(image, index) in images" :key="index">
+    <img v-lazy="image" />
+  </van-swipe-item>
+</van-swipe>
+```
+
+```javascript
+export default {
+  data() {
+    return {
+      images: [
+        'https://img.yzcdn.cn/1.jpg',
+        'https://img.yzcdn.cn/2.jpg'
+      ]
+    }
+  }
+}
+```
+
+### API
+
+| Attribute | Description | Type | Default | Accepted Values |
+|-----------|-----------|-----------|-------------|-------------|
+| autoplay | Autoplay interval (ms) | `Number` | - | - |
+| duration | Animation duration (ms) | `Number` | `500` | - |
+| showIndicators | Whether to show indocators | `Boolean` | `true` | - |
+| initialSwipe | Index of initial swipe, start from 0 | `Number` | `0` | - |
+
+### Event
+
+| Event | Description | Attribute |
+|-----------|-----------|-----------|
+| change | Triggered when current swipe change | index: index of current swipe |