Added missing processScheduledDelete method from Strategy interface

lib/Gedmo/Tree/Strategy.php

@@ -47,6 +47,15 @@ interface Strategy
      */
     function processScheduledUpdate($om, $object);
 
+    /**
+     * Operations on tree node delete
+     *
+     * @param object $om - object manager
+     * @param object $object - node
+     * @return void
+     */
+    function processScheduledDelete($om, $object);
+
     /**
      * Operations on tree node removal
      *