Refactor and modernize namespace declarations

Move all unit tests to namespace nfd::tests

Delete unused header core/algorithm.hpp

Change-Id: I5591f0c5f3bb5db67f8b45fae95471f8a555ca68
diff --git a/daemon/rib/readvertise/readvertise-destination.hpp b/daemon/rib/readvertise/readvertise-destination.hpp
index 1c4fb76..045483a 100644
--- a/daemon/rib/readvertise/readvertise-destination.hpp
+++ b/daemon/rib/readvertise/readvertise-destination.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2014-2019,  Regents of the University of California,
+ * Copyright (c) 2014-2022,  Regents of the University of California,
  *                           Arizona Board of Regents,
  *                           Colorado State University,
  *                           University Pierre & Marie Curie, Sorbonne University,
@@ -28,8 +28,7 @@
 
 #include "readvertised-route.hpp"
 
-namespace nfd {
-namespace rib {
+namespace nfd::rib {
 
 /** \brief a destination to readvertise into
  */
@@ -68,7 +67,6 @@
   bool m_isAvailable = false;
 };
 
-} // namespace rib
-} // namespace nfd
+} // namespace nfd::rib
 
 #endif // NFD_DAEMON_RIB_READVERTISE_READVERTISE_DESTINATION_HPP