Move sys_time fmt to date_time.cpp

Utilities/date_time.cpp

@@ -0,0 +1,11 @@
+#include "stdafx.h"
+#include "date_time.h"
+
+#include <chrono>
+
+template <>
+void fmt_class_string<std::chrono::sys_time<typename std::chrono::system_clock::duration>>::format(std::string& out, u64 arg)
+{
+	const std::time_t dateTime = std::chrono::system_clock::to_time_t(get_object(arg));
+	out += date_time::fmt_time("%Y-%m-%dT%H:%M:%S", dateTime);
+}