Post function - check if we have a delete_token

- some board functions can create automatic posts using the post
  function, such as when you move a thread to another board and it
  replies with the new thread's id. it doesn't make sense for these
  posts to have a delete_token, since they shouldn't be in spamnoticer,
  and a user will never delete them since it is no user's post.

- save it as null if it's not present

inc/functions.php

@@ -1085,7 +1085,7 @@ function post(array $post) {
         $query->bindValue(':slug', NULL);
     }
 
-    if ($config['spam_noticer']['enabled']) {
+    if ($config['spam_noticer']['enabled'] && isset($post['delete_token'])) {
         $query->bindValue(':delete_token', $post['delete_token']);
     } else {
         $query->bindValue(':delete_token', NULL);