Group emojis into packs in emoji picker

As https://kazv.moe/notice/AAL8n2AzoyWmYUZhJo .

build/build.js

@@ -18,6 +18,9 @@ console.log(
 var spinner = ora('building for production...')
 spinner.start()
 
+var updateEmoji = require('./update-emoji').updateEmoji
+updateEmoji()
+
 var assetsPath = path.join(config.build.assetsRoot, config.build.assetsSubDirectory)
 rm('-rf', assetsPath)
 mkdir('-p', assetsPath)