feat: 增加首頁評論數顯示

fix: 修復點擊toc後，滾動完toc的highlight在點擊的上一個元素
fix: 修復打賞按鈕Hover的bug close #473
improvement: 友情鏈接界面增加title顯示（top_img設為false時）
improvement: 優化toc顯示，當向上滾動時，導航欄不會遮擋 toc close #472
improvement: 升級facebook comment sdk版本

layout/includes/third-party/card-post-count/fb.pug

@@ -0,0 +1,15 @@
+script.
+  (()=>{
+    function loadFBComment () {
+      if (typeof FB === 'object') FB.XFBML.parse()
+      else {
+        let ele = document.createElement('script')
+        ele.setAttribute('src','https://connect.facebook.net/!{theme.facebook_comments.lang}/sdk.js#xfbml=1&version=v9.0')
+        ele.setAttribute('async', 'true')
+        ele.setAttribute('defer', 'true')
+        ele.setAttribute('crossorigin', 'anonymous')
+        document.body.appendChild(ele)
+      }
+    }
+    window.pjax ? loadFBComment() : window.addEventListener('load', loadFBComment)
+  })()