Implement library caching TitleInfo

* Cache sum of entry progress
* Cache cover_url
* Cache display_name
* Cache sort_opt

src/util/web.cr

@@ -120,6 +120,7 @@ macro get_and_save_sort_opt(dir)
 
     sort_opt = SortOptions.new sort_method, is_ascending
 
+    InfoCache.set_sort_opt {{dir}}, username, sort_opt
     TitleInfo.new {{dir}} do |info|
       info.sort_by[username] = sort_opt.to_tuple
       info.save