feat: 可設置首頁文章不顯示內容/description

feat: 主頁文章時間和文章頁文章時間可以配置顯示日期還是相對時間
feat: top_img 可配置 [留空（默認色）/顏色/漸變色/圖片鏈接/ false（不顯示top_img）]
feat: footer可配置背景 [留空/false(默認色)/顏色/漸變色/圖片鏈接/true(跟top_img一樣)]
improvement: preloader 在 pjax 下 每個頁面都會加載
improvement: 修改判斷，避免用户設置2個lightbox 而導致報錯（只能設置一個）
improvement: 精確時間顯示 （剛剛/幾分鐘前/幾小時前/幾天前/幾個月前）
improvement: 刪除不必要的語言文件和css
chore: update hexo-renderer-stylus to 2.0.1

layout/includes/mixins/post-ui.pug

@@ -57,21 +57,24 @@ mixin postUI(posts)
                   span.article-meta__link #[='•']
 
         //- Display the article introduction on homepage
-        if theme.index_post_content.method == 1
-          .content!= article.description
-        else if theme.index_post_content.method == 2
-          if article.description
+        case theme.index_post_content.method
+          when false
+            - break
+          when 1
             .content!= article.description
-          else
+          when 2
+            if article.description
+              .content!= article.description
+            else
+              - const content = strip_html(article.content)
+              - let expert = content.substring(0, theme.index_post_content.length) 
+              - content.length > theme.index_post_content.length ? expert += ' ...' : ''
+              .content!= expert
+          default
             - const content = strip_html(article.content)
             - let expert = content.substring(0, theme.index_post_content.length) 
             - content.length > theme.index_post_content.length ? expert += ' ...' : ''
             .content!= expert
-        else
-          - const content = strip_html(article.content)
-          - let expert = content.substring(0, theme.index_post_content.length) 
-          - content.length > theme.index_post_content.length ? expert += ' ...' : ''
-          .content!= expert
 
     if theme.ad && theme.ad.index
       if (index + 1) % 3 == 0