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/disqus.pug

@@ -0,0 +1,16 @@
+script.
+  (() => {
+    const getCount = () => {
+      if (window.DISQUSWIDGETS === undefined) {
+        var d = document, s = d.createElement('script');
+        s.src = 'https://!{theme.disqus.shortname}.disqus.com/count.js';
+        s.id = 'dsq-count-scr';
+        (d.head || d.body).appendChild(s);
+      } else {
+        DISQUSWIDGETS.getCount({reset: true});
+      }
+    }
+
+    window.pjax ? getCount() : window.addEventListener('load', getCount)
+
+  })()