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/route.hpp b/daemon/rib/route.hpp
index 9b0bead..eea42ee 100644
--- a/daemon/rib/route.hpp
+++ b/daemon/rib/route.hpp
@@ -35,8 +35,7 @@
 
 #include <type_traits>
 
-namespace nfd {
-namespace rib {
+namespace nfd::rib {
 
 /** \brief represents a route for a name prefix
  */
@@ -116,7 +115,6 @@
 std::ostream&
 operator<<(std::ostream& os, const Route& route);
 
-} // namespace rib
-} // namespace nfd
+} // namespace nfd::rib
 
 #endif // NFD_DAEMON_RIB_ROUTE_HPP