Add changyan count configuration (theme-next#570)

Author: yanickxia

_config.yml

@@ -610,6 +610,8 @@ changyan:
   enable: false
   appid:
   appkey:
+  # Show comments count
+  count: true
 
 # LiveRe comments system
 # You can get your uid from https://livere.com/insight/myCode (General web site)

scripts/filters/comment/changyan.js

@@ -19,7 +19,7 @@ hexo.extend.filter.register('theme_inject', injects => {
 // Add post_meta
 hexo.extend.filter.register('theme_inject', injects => {
   const config = hexo.theme.config.changyan;
-  if (!config.enable || !config.appid || !config.appkey) return;
+  if (!config.enable || !config.count || !config.appid || !config.appkey) return;
 
   injects.postMeta.raw('changyan', `
   {% if post.comments %}