!per,doc,sam #17574 #17626 make recovery a method, move lambda samples

+ LambdaDoc samples now in the docs project
= simplified internal state by removing recoveryPending
= recovery is now triggered in around* method, so user is free to use
  preStart freely - recovery works even if one forgets to call super on
  preStart

akka-persistence/src/test/scala/akka/persistence/PersistentViewSpec.scala

@@ -14,8 +14,7 @@ object PersistentViewSpec {
 
   private class TestPersistentActor(name: String, probe: ActorRef) extends NamedPersistentActor(name) {
     def receiveCommand = {
-      case msg ⇒
-        persist(msg) { m ⇒ probe ! s"${m}-${lastSequenceNr}" }
+      case msg ⇒ persist(msg) { m ⇒ probe ! s"${m}-${lastSequenceNr}" }
     }
 
     override def receiveRecover: Receive = {