remove app argument from Dispatchers

(cascading into all dispatchers, mailboxes, other stuff; had to move
deadLetter stuff to ActorSystem again and split its initialization due
to cyclic dependency)

akka-actor/src/main/scala/akka/dispatch/Dispatcher.scala

@@ -9,6 +9,8 @@ import java.util.concurrent.atomic.AtomicReference
 import java.util.concurrent.{ TimeUnit, ExecutorService, RejectedExecutionException, ConcurrentLinkedQueue }
 import akka.actor.{ ActorCell, ActorKilledException }
 import akka.actor.ActorSystem
+import akka.event.EventStream
+import akka.actor.Scheduler
 
 /**
  * Default settings are:
@@ -64,14 +66,16 @@ import akka.actor.ActorSystem
  *                   Larger values (or zero or negative) increase throughput, smaller values increase fairness
  */
 class Dispatcher(
-  _app: ActorSystem,
+  _deadLetterMailbox: Mailbox,
+  _eventStream: EventStream,
+  _scheduler: Scheduler,
   val name: String,
   val throughput: Int,
   val throughputDeadlineTime: Int,
   val mailboxType: MailboxType,
   executorServiceFactoryProvider: ExecutorServiceFactoryProvider,
   val timeoutMs: Long)
-  extends MessageDispatcher(_app) {
+  extends MessageDispatcher(_deadLetterMailbox, _eventStream, _scheduler) {
 
   protected[akka] val executorServiceFactory = executorServiceFactoryProvider.createExecutorServiceFactory(name)
   protected[akka] val executorService = new AtomicReference[ExecutorService](new LazyExecutorServiceWrapper(executorServiceFactory.createExecutorService))
@@ -93,7 +97,7 @@ class Dispatcher(
       executorService.get() execute invocation
     } catch {
       case e: RejectedExecutionException ⇒
-        app.eventStream.publish(Warning(this, e.toString))
+        eventStream.publish(Warning(this, e.toString))
         throw e
     }
   }
@@ -120,7 +124,7 @@ class Dispatcher(
         } catch {
           case e: RejectedExecutionException ⇒
             try {
-              app.eventStream.publish(Warning(this, e.toString))
+              eventStream.publish(Warning(this, e.toString))
             } finally {
               mbox.setAsIdle()
             }