move all Ask stuff to akka.pattern

- remove ?(msg, timeout), should always use ?(msg)(timeout) because of
  Scala’s only Martin-acknowledged design flaw of being able to pass
  tuples into single-arg methods without adding another pair of parens
- put a provider into all actor refs, because they all are created by
  and associated with one
- treat all terminated refs equally: tell(msg) and return broken promise

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

@@ -166,7 +166,7 @@ private[akka] class RemoteActorRef private[akka] (
   val path: ActorPath,
   val getParent: InternalActorRef,
   loader: Option[ClassLoader])
-  extends InternalActorRef with RemoteRef with ActorRefWithProvider {
+  extends InternalActorRef with RemoteRef {
 
   def getChild(name: Iterator[String]): InternalActorRef = {
     val s = name.toStream