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/fw/asf-measurements.hpp b/daemon/fw/asf-measurements.hpp
index 1d2b90f..bfed7ca 100644
--- a/daemon/fw/asf-measurements.hpp
+++ b/daemon/fw/asf-measurements.hpp
@@ -33,9 +33,7 @@
 
 #include <unordered_map>
 
-namespace nfd {
-namespace fw {
-namespace asf {
+namespace nfd::fw::asf {
 
 /** \brief Strategy information for each face in a namespace
 */
@@ -217,8 +215,6 @@
   shared_ptr<const ndn::util::RttEstimator::Options> m_rttEstimatorOpts;
 };
 
-} // namespace asf
-} // namespace fw
-} // namespace nfd
+} // namespace nfd::fw::asf
 
 #endif // NFD_DAEMON_FW_ASF_MEASUREMENTS_HPP