Remove unused cruft

program/include/rcmail.php

@@ -594,7 +594,6 @@ class rcmail
       return;
 
     $this->imap = new rcube_imap();
-    $this->imap->debug_level = $this->config->get('debug_level');
     $this->imap->skip_deleted = $this->config->get('skip_deleted');
 
     // enable caching of imap data

program/include/rcube_imap.php

@@ -32,7 +32,6 @@
  */
 class rcube_imap
 {
-    public $debug_level = 1;
     public $skip_deleted = false;
     public $page_size = 10;
     public $list_page = 1;