breaking changes: 移除最新評論的評論服務商選擇，默認為第一個評論服務商

feat: 增加 waline avatarCDN 配置（最新評論也會更新）
feat: archives 的 標題 在 menu 配置中獲取
fix: 修復文章頁 mathjax 因字體小導致顯示重疊的 bug close #587
fix: 修復 mathjax 在列表下，導致 列表沒有樣式的 bug  close #586
improvement: 減少卡頓，apple 裝置首頁背景 background-attachment 設為 scroll

_config.yml

@@ -274,6 +274,7 @@ comments:
 # https://disqus.com/
 disqus:
   shortname:
+  apikey: # For newest comments widget
 
 # Alternative Disqus - Render comments with Disqus API
 # DisqusJS 評論系統，可以實現在網路審查地區載入 Disqus 評論列表，兼容原版
@@ -331,6 +332,7 @@ valine:
 waline:
   serverURL: # Waline server address url
   avatar: monsterid # gravatar style https://zh-tw.gravatar.com/site/implement/images/#default-image
+  avatarCDN: # Gravatar CDN baseURL
   bg: # waline background
   visitor: false
   option:
@@ -693,17 +695,6 @@ newest_comments:
   limit: 6
   storage: 10 # unit: mins, save data to localStorage
   avatar: true
-  # You can only choose one, or neither
-  valine: false
-  github_issues:
-    enable: false
-    repo:
-  disqus:
-    enable: false
-    forum:
-    api_key:
-  twikoo: false
-  waline: false
 
 # Bottom right button (右下角按鈕)
 # --------------------------------------

layout/includes/head.pug

@@ -1,5 +1,5 @@
 - var pageTitle
-- if (is_archive()) pageTitle = _p('page.archives')
+- if (is_archive()) pageTitle = fragment_cache('findArchivesTitle', function(){return findArchivesTitle(theme.menu);})
 - else if (is_tag()) pageTitle = _p('page.tag') + ': ' + page.tag
 - else if (is_category()) pageTitle = _p('page.category') + ': ' + page.category
 - else if (is_month()) pageTitle += ': ' + page.month + '/' + page.year

layout/includes/header/index.pug

@@ -19,7 +19,7 @@ if !theme.disable_top_img && page.top_img !== false
   if top_img !== false
     - var imgSource = top_img && top_img.indexOf('/') !== -1 ? `background-image: url('${url_for(top_img)}')` : `background: ${top_img}`
     - var bg_img = top_img ? imgSource : ''
-    - var site_title = is_archive() ? _p('page.archives') : page.title || page.tag || page.category || config.title
+    - var site_title = is_archive() ? fragment_cache('findArchivesTitle', function(){return findArchivesTitle(theme.menu);}) : page.title || page.tag || page.category || config.title
     - var isHomeClass = is_home() ? 'full_page' : 'not-home-page'
     - is_post() ? isHomeClass = 'post-bg' : isHomeClass
   else