restore behavior of Future.as[T] and .asSilently[T] (fixes #1088)

- implement both methods equivalently directly on Future
- remove implicit conversion futureToAnyOptionAsTypedOption
- update docs accordingly

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

@@ -377,6 +377,37 @@ sealed trait Future[+T] extends japi.Future[T] {
    */
   def await(atMost: Duration): Future[T]
 
+  /**
+   * Await completion of this Future and return its value if it conforms to A's
+   * erased type. Will throw a ClassCastException if the value does not
+   * conform, or any exception the Future was completed with. Will return None
+   * in case of a timeout.
+   */
+  def as[A](implicit m: Manifest[A]): Option[A] = {
+    try await catch { case _: FutureTimeoutException ⇒ }
+    value match {
+      case None           ⇒ None
+      case Some(Left(ex)) ⇒ throw ex
+      case Some(Right(v)) ⇒ Some(BoxedType(m.erasure).cast(v).asInstanceOf[A])
+    }
+  }
+
+  /**
+   * Await completion of this Future and return its value if it conforms to A's
+   * erased type, None otherwise. Will throw any exception the Future was
+   * completed with. Will return None in case of a timeout.
+   */
+  def asSilently[A](implicit m: Manifest[A]): Option[A] = {
+    try await catch { case _: FutureTimeoutException ⇒ }
+    value match {
+      case None           ⇒ None
+      case Some(Left(ex)) ⇒ throw ex
+      case Some(Right(v)) ⇒
+        try Some(BoxedType(m.erasure).cast(v).asInstanceOf[A])
+        catch { case _: ClassCastException ⇒ None }
+    }
+  }
+
   /**
    * Tests whether this Future has been completed.
    */