[Improvement] optimize staticClass (#337)

* 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

* [bugfix] Search box-sizing wrong

* [Doc] update vant-demo respo

* [Doc] translate theme & demo pages

* [Doc] add Internationalization document

* [bugfix] remove unnecessary props

* [fix] optimize clickoutside

* [new feature] optimize find-parent

* [new feature]: change document title accordinng to language

* [new feature] Pagination code review

* [improvement] adjust icon-font unicode

* [improvement] Icon spinner color inherit

* [improvement] icon default width

* [bugfix] DateTimePicker validate date props

* [bugfix] Tab item text ellipsis

* [improvement] optimize single line ellipsis

* [Improvement] optimzie staticClass

packages/picker/index.vue

@@ -7,16 +7,16 @@
         <div v-if="title" class="van-picker__title">{{ title }}</div>
       </slot>
     </div>
-    <div class="van-picker__columns" :class="['van-picker__columns--' + columns.length]">
+    <div class="van-picker__columns" :class="`van-picker__columns--${columns.length}`">
       <van-picker-column
         v-for="(item, index) in columns"
         :key="index"
         v-model="values[index]"
         :values="item.values"
-        :class-name="item.className"
+        :className="item.className"
         :itemHeight="itemHeight"
-        :visible-item-count="visibileColumnCount"
-        :value-key="valueKey"
+        :visibleItemCount="visibileColumnCount"
+        :valueKey="valueKey"
         @columnChange="columnValueChange(index)"
       />
       <div class="van-picker-center-highlight" :style="{ height: itemHeight + 'px', marginTop: -itemHeight / 2 + 'px' }"></div>