added a timer abstraction and replaced the use of boost.date_time. the timers used now are QueryPerformanceCounter on windows, mach_absolute_time on darwin and currently falls back on boost.date_time on other platforms. This has the advantage of being a monotonic clock, and also slightly more efficient

src/logger.cpp

@@ -73,7 +73,7 @@ namespace libtorrent { namespace
 		void log_timestamp()
 		{
 			using namespace boost::posix_time;
-			std::string now(to_simple_string(second_clock::universal_time()));
+			std::string now(to_simple_string(second_clock::local_time()));
 			m_file << now << ": ";
 		}