votes: add vote buttons beneath thumbnails.

Add upvote and downvote buttons beneath thumbnails on the post index page.

This is disabled by default. To enable it, click the "..." menu in the top
right of the page, then click "Show scores".

This is currently a per-search setting, not an account setting. If you
enable it in one tab, it won't be enabled in other tabs.

app/logical/post_sets/post.rb

@@ -7,10 +7,10 @@ module PostSets
     MAX_PER_PAGE = 200
     MAX_SIDEBAR_TAGS = 25
 
-    attr_reader :page, :random, :format, :tag_string, :query, :normalized_query
+    attr_reader :page, :random, :format, :tag_string, :query, :normalized_query, :view
     delegate :post_count, to: :normalized_query
 
-    def initialize(tags, page = 1, per_page = nil, user: CurrentUser.user, random: false, format: "html")
+    def initialize(tags, page = 1, per_page = nil, user: CurrentUser.user, random: false, format: "html", view: "simple")
       @query = PostQueryBuilder.new(tags, user, tag_limit: user.tag_query_limit, safe_mode: CurrentUser.safe_mode?, hide_deleted_posts: user.hide_deleted_posts?)
       @normalized_query = query.normalized_query
       @tag_string = tags
@@ -18,6 +18,7 @@ module PostSets
       @per_page = per_page
       @random = random.to_s.truthy?
       @format = format.to_s
+      @view = view.presence || "simple"
     end
 
     def humanized_tag_string
@@ -107,7 +108,7 @@ module PostSets
         if is_random?
           get_random_posts.paginate(page, search_count: false, limit: per_page, max_limit: max_per_page).load
         else
-          normalized_query.paginated_posts(page, includes: :media_asset, count: post_count, search_count: !post_count.nil?, limit: per_page, max_limit: max_per_page).load
+          normalized_query.paginated_posts(page, includes: includes, count: post_count, search_count: !post_count.nil?, limit: per_page, max_limit: max_per_page).load
         end
       end
     end
@@ -139,6 +140,18 @@ module PostSets
       end
     end
 
+    def show_votes?
+      view == "score"
+    end
+
+    def includes
+      if show_votes?
+        [:media_asset, :vote_by_current_user]
+      else
+        [:media_asset]
+      end
+    end
+
     def search_stats
       {
         query: normalized_query.to_s,