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.hpp b/daemon/rib/readvertise/readvertise.hpp
index aeaa823..88b11aa 100644
--- a/daemon/rib/readvertise/readvertise.hpp
+++ b/daemon/rib/readvertise/readvertise.hpp
@@ -31,8 +31,7 @@
 #include "readvertised-route.hpp"
 #include "rib/rib.hpp"
 
-namespace nfd {
-namespace rib {
+namespace nfd::rib {
 
 /** \brief readvertise a subset of routes to a destination according to a policy
  *
@@ -81,7 +80,6 @@
   signal::ScopedConnection m_removeRouteConn;
 };
 
-} // namespace rib
-} // namespace nfd
+} // namespace nfd::rib
 
 #endif // NFD_DAEMON_RIB_READVERTISE_READVERTISE_HPP