Introduce parental supervision, BUT TESTS ARE STILL FAILING

- every actor is now supervised, where the root of the tree is
  app.guardian, which has its supervisor field set to a special ActorRef
  obtained from provider.theOneWhoWalksTheBubblesOfSpaceTime (this name
  is meant to indicate that this ref is outside of the universe, cf.
  Michio Kaku)
- changed all tests to obtain specially supervised children (i.e. not
  top-level) via (supervisor ? Props).as[ActorRef].get
- add private[akka] ScalaActorRef.sendSystemMessage for sending
  Supervise()
- everything routing or remote is broken wrt. supervision, as that was
  not “properly” implemented to begin with, will be tackled after
  app/supervision/eventbus/AkkaSpec are stabilized enough

akka-remote/src/main/scala/akka/remote/RemoteActorRefProvider.scala

@@ -31,6 +31,8 @@ class RemoteActorRefProvider(val app: AkkaApplication) extends ActorRefProvider
   import java.util.concurrent.ConcurrentHashMap
   import akka.dispatch.Promise
 
+  private[akka] val theOneWhoWalksTheBubblesOfSpaceTime: ActorRef = new UnsupportedActorRef {}
+
   val local = new LocalActorRefProvider(app)
   val remote = new Remote(app)
 
@@ -44,10 +46,8 @@ class RemoteActorRefProvider(val app: AkkaApplication) extends ActorRefProvider
   def defaultDispatcher = app.dispatcher
   def defaultTimeout = app.AkkaConfig.ActorTimeout
 
-  def actorOf(props: Props, address: String): ActorRef = actorOf(props, address, false)
-
-  def actorOf(props: Props, address: String, systemService: Boolean): ActorRef =
-    if (systemService) local.actorOf(props, address, systemService)
+  def actorOf(props: Props, supervisor: ActorRef, address: String, systemService: Boolean): ActorRef =
+    if (systemService) local.actorOf(props, supervisor, address, systemService)
     else {
       val newFuture = Promise[ActorRef](5000)(defaultDispatcher) // FIXME is this proper timeout?
 
@@ -71,7 +71,7 @@ class RemoteActorRefProvider(val app: AkkaApplication) extends ActorRefProvider
 
                 if (isReplicaNode) {
                   // we are on one of the replica node for this remote actor
-                  new LocalActorRef(app, props, address, false)
+                  new LocalActorRef(app, props, supervisor, address, false)
                 } else {
 
                   // we are on the single "reference" node uses the remote actors on the replica nodes
@@ -115,10 +115,10 @@ class RemoteActorRefProvider(val app: AkkaApplication) extends ActorRefProvider
 
                   connections.keys foreach { useActorOnNode(_, address, props.creator) }
 
-                  actorOf(RoutedProps(routerFactory = routerFactory, connectionManager = connectionManager), address)
+                  actorOf(RoutedProps(routerFactory = routerFactory, connectionManager = connectionManager), supervisor, address)
                 }
 
-              case deploy ⇒ local.actorOf(props, address, systemService)
+              case deploy ⇒ local.actorOf(props, supervisor, address, systemService)
             }
           } catch {
             case e: Exception ⇒
@@ -139,7 +139,8 @@ class RemoteActorRefProvider(val app: AkkaApplication) extends ActorRefProvider
   /**
    * Copied from LocalActorRefProvider...
    */
-  def actorOf(props: RoutedProps, address: String): ActorRef = {
+  // FIXME: implement supervision
+  def actorOf(props: RoutedProps, supervisor: ActorRef, address: String): ActorRef = {
     if (props.connectionManager.isEmpty) throw new ConfigurationException("RoutedProps used for creating actor [" + address + "] has zero connections configured; can't create a router")
     new RoutedActorRef(props, address)
   }
@@ -244,6 +245,8 @@ private[akka] case class RemoteActorRef private[akka] (
 
   def isShutdown: Boolean = !running
 
+  protected[akka] def sendSystemMessage(message: SystemMessage): Unit = unsupported
+
   def postMessageToMailbox(message: Any, channel: UntypedChannel) {
     val chSender = if (channel.isInstanceOf[ActorRef]) Some(channel.asInstanceOf[ActorRef]) else None
     remote.send[Any](message, chSender, None, remoteAddress, true, this, loader)