breaking changes: algolia 升級至 v4

feat:  本地搜索增加數據庫加載中和搜索中 loading 顯示
feat: 更改文章美化後,列表的顯示效果 closed #693 closed #686
improvement: UI 微調

layout/includes/header/nav.pug

@@ -7,7 +7,7 @@ nav#nav
       #search-button
         a.site-page.social-icon.search
           i.fas.fa-search.fa-fw
-          span=' '+_p('search')
+          span=' '+_p('search.title')
     !=partial('includes/header/menu_item', {}, {cache: true})
 
     #toggle-menu