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/rib-update.hpp b/daemon/rib/rib-update.hpp
index bcdb342..70bbe1e 100644
--- a/daemon/rib/rib-update.hpp
+++ b/daemon/rib/rib-update.hpp
@@ -29,8 +29,7 @@
 #include "core/common.hpp"
 #include "route.hpp"
 
-namespace nfd {
-namespace rib {
+namespace nfd::rib {
 
 /**
  * \brief Represents a route that will be added to or removed from a namespace
@@ -118,7 +117,6 @@
 std::ostream&
 operator<<(std::ostream& os, const RibUpdate& update);
 
-} // namespace rib
-} // namespace nfd
+} // namespace nfd::rib
 
 #endif // NFD_DAEMON_RIB_RIB_UPDATE_HPP