[improvement]: Dialog：使Dialog中的Button支持open-type，并更新了相应的示例 (#247)

example/pages/dialog/index.js

@@ -32,6 +32,10 @@ Page({
         text: '现金支付',
         color: 'red',
         type: 'cash'
+      }, {
+        text: '分享',
+        type: 'share',
+        openType: 'share'
       }, {
         text: '微信支付',
         color: '#3CC51F',
@@ -59,6 +63,10 @@ Page({
         text: '微信支付',
         color: '#3CC51F',
         type: 'wechat'
+      }, {
+        text: '分享',
+        type: 'share',
+        openType: 'share'
       }, {
         text: '取消',
         type: 'cancel'
@@ -66,5 +74,12 @@ Page({
     }).then(({ type }) => {
       console.log('=== dialog with vertical buttons ===', `type: ${type}`);
     });
-  }
+  },
+
+  onShareAppMessage() {
+    return {
+      title: 'ZanUI-WeApp',
+      imageUrl: 'https://img.yzcdn.cn/public_files/2017/02/06/ee0ebced79a80457d77ce71c7d414c74.png'
+    };
+  },
 });

packages/dialog/index.wxml

@@ -23,6 +23,7 @@
           class="zan-dialog__button"
           custom-class="{{ index === 0 ? 'zan-dialog__button-inside--first' : 'zan-dialog__button-inside' }}"
           data-type="{{ item.type }}"
+          open-type="{{ item.openType }}"
           bind:btnclick="handleButtonClick"
         >
           <view