[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/demos/views/image-preview.vue

@@ -0,0 +1,51 @@
+<template>
+  <demo-section>
+    <demo-block :title="$t('basicUsage')">
+      <van-button @click="showImagePreview">{{ $t('button1') }}</van-button>
+    </demo-block>
+
+    <demo-block :title="$t('button2')">
+      <van-button @click="showImagePreview(1)">{{ $t('button2') }}</van-button>
+    </demo-block>
+  </demo-section>
+</template>
+
+<script>
+import { ImagePreview } from 'packages';
+
+export default {
+  i18n: {
+    'zh-CN': {
+      button1: '预览图片',
+      button2: '指定初始位置'
+    },
+    'en-US': {
+      button1: 'Show Images',
+      button2: 'Custom Start Position'
+    }
+  },
+
+  methods: {
+    showImagePreview(position) {
+      ImagePreview([
+        'https://img.yzcdn.cn/upload_files/2017/03/15/FkubrzN7AgGwLlTeb1E89-T_ZjBg.png',
+        'https://img.yzcdn.cn/upload_files/2017/03/14/FmTPs0SeyQaAOSK1rRe1sL8RcwSY.jpeg',
+        'https://img.yzcdn.cn/upload_files/2017/03/15/FvexrWlG_WxtCE9Omo5l27n_mAG_.jpeg'
+      ], typeof position === 'number' ? position : 0);
+    }
+  }
+};
+</script>
+
+<style lang="postcss">
+.demo-image-preview {
+  .van-button {
+    margin-left: 15px;
+  }
+}
+.van-image-preview {
+  img {
+    pointer-events: none;
+  }
+}
+</style>