-str - Improvements and renames in internal streams classes

* Renames Module.grow -> Module.compose
 * Renames Module.connect -> Module.wire
 * Renames Module.growConnect -> Module.fuse
 * Renames Module.wrap -> Module.nest

 * Adds explicit identity equals and hashCode to InPort and OutPort

 * Reimplements many of the Source factories to avoid copying

 * Documents Module.compose, Module.fuse, Module.wire and Module.nest

 * Removes Attributes.nameLifted

 * Optimizes Attributes.nameOrDefault

akka-stream/src/main/scala/akka/stream/ActorMaterializer.scala

@@ -129,12 +129,11 @@ object ActorMaterializer {
    * INTERNAL API
    */
   private[akka] def downcast(materializer: Materializer): ActorMaterializer =
-    materializer match {
+    materializer match { //FIXME this method is going to cause trouble for other Materializer implementations
       case m: ActorMaterializer ⇒ m
       case _ ⇒ throw new IllegalArgumentException(s"required [${classOf[ActorMaterializer].getName}] " +
         s"but got [${materializer.getClass.getName}]")
     }
-
 }
 
 /**