Move repositories to 'repos/' subdirectory

This patch changes the top-level directory layout as a preparatory
step for improving the tools for managing 3rd-party source codes.
The rationale is described in the issue referenced below.

Issue #1082

repos/hello_tutorial/src/hello/server/main.cc

@@ -0,0 +1,93 @@
+/*
+ * \brief  Main program of the Hello server
+ * \author Björn Döbel
+ * \date   2008-03-20
+ */
+
+/*
+ * Copyright (C) 2008-2013 Genode Labs GmbH
+ *
+ * This file is part of the Genode OS framework, which is distributed
+ * under the terms of the GNU General Public License version 2.
+ */
+
+#include <base/printf.h>
+#include <base/env.h>
+#include <base/sleep.h>
+#include <cap_session/connection.h>
+#include <root/component.h>
+#include <hello_session/hello_session.h>
+#include <base/rpc_server.h>
+
+namespace Hello {
+
+	struct Session_component : Genode::Rpc_object<Session>
+	{
+		void say_hello() {
+			PDBG("I am here... Hello."); }
+
+		int add(int a, int b) {
+			return a + b; }
+	};
+
+	class Root_component : public Genode::Root_component<Session_component>
+	{
+		protected:
+
+			Hello::Session_component *_create_session(const char *args)
+			{
+				PDBG("creating hello session.");
+				return new (md_alloc()) Session_component();
+			}
+
+		public:
+
+			Root_component(Genode::Rpc_entrypoint *ep,
+			               Genode::Allocator *allocator)
+			: Genode::Root_component<Session_component>(ep, allocator)
+			{
+				PDBG("Creating root component.");
+			}
+	};
+}
+
+
+using namespace Genode;
+
+int main(void)
+{
+	/*
+	 * Get a session for the parent's capability service, so that we
+	 * are able to create capabilities.
+	 */
+	Cap_connection cap;
+
+	/*
+	 * A sliced heap is used for allocating session objects - thereby we
+	 * can release objects separately.
+	 */
+	static Sliced_heap sliced_heap(env()->ram_session(),
+	                               env()->rm_session());
+
+	/*
+	 * Create objects for use by the framework.
+	 *
+	 * An 'Rpc_entrypoint' is created to announce our service's root
+	 * capability to our parent, manage incoming session creation
+	 * requests, and dispatch the session interface. The incoming RPC
+	 * requests are dispatched via a dedicated thread. The 'STACK_SIZE'
+	 * argument defines the size of the thread's stack. The additional
+	 * string argument is the name of the entry point, used for
+	 * debugging purposes only.
+	 */
+	enum { STACK_SIZE = 4096 };
+	static Rpc_entrypoint ep(&cap, STACK_SIZE, "hello_ep");
+
+	static Hello::Root_component hello_root(&ep, &sliced_heap);
+	env()->parent()->announce(ep.manage(&hello_root));
+
+	/* We are done with this and only act upon client requests now. */
+	sleep_forever();
+
+	return 0;
+}

repos/hello_tutorial/src/hello/server/target.mk

@@ -0,0 +1,3 @@
+TARGET = hello_server
+SRC_CC = main.cc
+LIBS   = base