[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/progress.vue

@@ -0,0 +1,48 @@
+<template>
+  <demo-section>
+    <demo-block :title="$t('basicUsage')">
+      <van-progress :percentage="0" />
+      <van-progress :percentage="46" />
+      <van-progress :percentage="100" />
+    </demo-block>
+
+    <demo-block :title="$t('title2')">
+      <van-progress inactive :percentage="0" />
+      <van-progress inactive :percentage="46" />
+      <van-progress inactive :percentage="100" />
+    </demo-block>
+
+    <demo-block :title="$t('title3')">
+      <van-progress :pivotText="$t('red')" color="#ed5050" :percentage="26" />
+      <van-progress :pivotText="$t('orange')" color="#f60" :percentage="46" />
+      <van-progress :pivotText="$t('yellow')" color="#f09000" :percentage="66" />
+    </demo-block>
+  </demo-section>
+</template>
+
+<script>
+export default {
+  i18n: {
+    'zh-CN': {
+      title2: '进度条置灰',
+      title3: '样式定制'
+    },
+    'en-US': {
+      title2: 'Inactive',
+      title3: 'Custom Style'
+    }
+  }
+}
+</script>
+
+<style lang="postcss">
+.demo-progress {
+  .van-progress {
+    margin: 20px 10px;
+
+    &:first-of-type {
+      margin-top: 10px;
+    }
+  }
+} 
+</style>