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/strategy-info.hpp b/daemon/fw/strategy-info.hpp
index 49b5b95..db6e9e6 100644
--- a/daemon/fw/strategy-info.hpp
+++ b/daemon/fw/strategy-info.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2014-2021,  Regents of the University of California,
+ * Copyright (c) 2014-2022,  Regents of the University of California,
  *                           Arizona Board of Regents,
  *                           Colorado State University,
  *                           University Pierre & Marie Curie, Sorbonne University,
@@ -28,8 +28,7 @@
 
 #include "core/common.hpp"
 
-namespace nfd {
-namespace fw {
+namespace nfd::fw {
 
 /** \brief Contains arbitrary information placed by the forwarding strategy on table entries
  */
@@ -51,7 +50,6 @@
   StrategyInfo() = default;
 };
 
-} // namespace fw
-} // namespace nfd
+} // namespace nfd::fw
 
 #endif // NFD_DAEMON_FW_STRATEGY_INFO_HPP