rib: turn RibUpdate into an aggregate

And move it together with RibUpdateList and RibUpdateBatch.
Also remove a few unused functions from RibEntry.

Change-Id: Id4f79fda27d3bffb8411e2a95c24154e2cb80c4f
diff --git a/daemon/mgmt/rib-manager.hpp b/daemon/mgmt/rib-manager.hpp
index 87de627..d6b6ebe 100644
--- a/daemon/mgmt/rib-manager.hpp
+++ b/daemon/mgmt/rib-manager.hpp
@@ -27,7 +27,6 @@
 #define NFD_DAEMON_MGMT_RIB_MANAGER_HPP
 
 #include "manager-base.hpp"
-#include "rib/route.hpp"
 
 #include <ndn-cxx/mgmt/nfd/controller.hpp>
 #include <ndn-cxx/mgmt/nfd/face-event-notification.hpp>
@@ -39,8 +38,9 @@
 namespace nfd {
 
 namespace rib {
+class Route;
 class Rib;
-class RibUpdate;
+struct RibUpdate;
 } // namespace rib
 
 /**