Add base/swap.hpp and Swap() function.

base/base.pro

@@ -42,6 +42,7 @@ HEADERS += \
     logging.hpp \
     start_mem_debug.hpp \
     stop_mem_debug.hpp \
+    swap.hpp \
     thread.hpp \
     mutex.hpp \
     casts.hpp \

base/swap.hpp

@@ -0,0 +1,11 @@
+#pragma once
+
+#include "../std/algorithm.hpp"
+
+// Calls swap() function using argument dependant lookup.
+// Do NOT override this function, but override swap() function instead!
+template <typename T> inline void Swap(T & a, T & b)
+{
+  using std::swap;
+  swap(a, b);
+}