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/face/lp-reliability.hpp b/daemon/face/lp-reliability.hpp
index c83b0bc..17b2e44 100644
--- a/daemon/face/lp-reliability.hpp
+++ b/daemon/face/lp-reliability.hpp
@@ -34,8 +34,7 @@
 
 #include <queue>
 
-namespace nfd {
-namespace face {
+namespace nfd::face {
 
 class GenericLinkService;
 
@@ -221,7 +220,6 @@
 std::ostream&
 operator<<(std::ostream& os, const FaceLogHelper<LpReliability>& flh);
 
-} // namespace face
-} // namespace nfd
+} // namespace nfd::face
 
 #endif // NFD_DAEMON_FACE_LP_RELIABILITY_HPP