add preprocessor for RST docs, see #2461 and #2431

The idea is to filter the sources, replacing @<var>@ occurrences with
the mapping for <var> (which is currently hard-coded). @@ -> @. In order
to make this work, I had to move the doc sources one directory down
(into akka-docs/rst) so that the filtered result could be in a sibling
directory so that relative links (to _sphinx plugins or real code) would
continue to work.

While I was at it I also changed it so that WARNINGs and ERRORs are not
swallowed into the debug dump anymore but printed at [warn] level
(minimum).

One piece of fallout is that the (online) html build is now run after
the normal one, not in parallel.

akka-docs/rst/java/code/docs/jrouting/RouterViaProgramExample.java

@@ -0,0 +1,96 @@
+/**
+ * Copyright (C) 2009-2012 Typesafe Inc. <http://www.typesafe.com>
+ */
+package docs.jrouting;
+
+import akka.routing.RoundRobinRouter;
+import akka.routing.DefaultResizer;
+import akka.remote.routing.RemoteRouterConfig;
+import akka.actor.ActorRef;
+import akka.actor.Props;
+import akka.actor.UntypedActor;
+import akka.actor.ActorSystem;
+import akka.actor.Address;
+import akka.actor.AddressFromURIString;
+import java.util.Arrays;
+
+public class RouterViaProgramExample {
+
+  public static class ExampleActor extends UntypedActor {
+    public void onReceive(Object msg) {
+      if (msg instanceof Message) {
+        Message message = (Message) msg;
+        System.out.println(String.format("Received %s in router %s", message.getNbr(), getSelf().path().name()));
+      } else {
+        unhandled(msg);
+      }
+    }
+
+    public static class Message {
+      private final int nbr;
+
+      public Message(int nbr) {
+        this.nbr = nbr;
+      }
+
+      public int getNbr() {
+        return nbr;
+      }
+
+    }
+  }
+
+  public static void main(String... args) {
+    ActorSystem system = ActorSystem.create("RPE");
+    //#programmaticRoutingNrOfInstances
+    int nrOfInstances = 5;
+    ActorRef router1 = system.actorOf(new Props(ExampleActor.class).withRouter(new RoundRobinRouter(nrOfInstances)));
+    //#programmaticRoutingNrOfInstances
+    for (int i = 1; i <= 6; i++) {
+      router1.tell(new ExampleActor.Message(i), null);
+    }
+
+    //#programmaticRoutingRoutees
+    ActorRef actor1 = system.actorOf(new Props(ExampleActor.class));
+    ActorRef actor2 = system.actorOf(new Props(ExampleActor.class));
+    ActorRef actor3 = system.actorOf(new Props(ExampleActor.class));
+    Iterable<ActorRef> routees = Arrays.asList(new ActorRef[] { actor1, actor2, actor3 });
+    ActorRef router2 = system.actorOf(new Props().withRouter(RoundRobinRouter.create(routees)));
+    //#programmaticRoutingRoutees
+    for (int i = 1; i <= 6; i++) {
+      router2.tell(new ExampleActor.Message(i), null);
+    }
+
+    //#programmaticRoutingWithResizer
+    int lowerBound = 2;
+    int upperBound = 15;
+    DefaultResizer resizer = new DefaultResizer(lowerBound, upperBound);
+    ActorRef router3 = system.actorOf(new Props(ExampleActor.class).withRouter(new RoundRobinRouter(nrOfInstances)));
+    //#programmaticRoutingWithResizer
+    for (int i = 1; i <= 6; i++) {
+      router3.tell(new ExampleActor.Message(i), null);
+    }
+    
+    //#remoteRoutees
+    Address addr1 = new Address("akka", "remotesys", "otherhost", 1234);
+    Address addr2 = AddressFromURIString.parse("akka://othersys@anotherhost:1234");
+    Address[] addresses = new Address[] { addr1, addr2 };
+    ActorRef routerRemote = system.actorOf(new Props(ExampleActor.class)
+      .withRouter(new RemoteRouterConfig(new RoundRobinRouter(5), addresses)));
+    //#remoteRoutees
+  }
+  
+  private class CompileCheckJavaDocsForRouting extends UntypedActor {
+
+    @Override
+    public void onReceive(Object o) {
+      //#reply-with-parent
+      getSender().tell("reply", getContext().parent()); // replies go to router
+      //#reply-with-parent
+      //#reply-with-self
+      getSender().tell("reply", getSelf()); // replies go to this actor
+      //#reply-with-self
+    }
+    
+  }
+}