add userboxes and use them instead of flash

views/user/delete_confirm.etlua

@@ -4,8 +4,8 @@
   <p>This cannot be undone. This will not delete your posts, only anonymize them.</p>
   <p>If you are sure, please type your password below.</p>
 
-  <% if err then %>
-    <h2><%= err %></h2>
+  <% if infobox then %>
+    <% render("views.common.infobox", infobox) %>
   <% end %>
 
   <form method="post" action="<%= url_for("user_delete", {username = me.username}) %>">