Merge pull request #136 from samsonasik/add-priority-in-interface

listener call priority in PennyEvmInterface

src/Event/PennyEvmInterface.php

@@ -15,6 +15,7 @@ public function trigger(PennyEventInterface $event);
      *
      * @param string $eventName Specific event name
      * @param callable $listener Function to call
+     * @param int $priority listener call priority
      */
-    public function attach($eventName, callable $listener);
+    public function attach($eventName, callable $listener, $priority = 0);
 }