* Change win32 client Sys_Sleep so it ONLY sleeps since before it was waking on

more or less any input event; fine for the server, not so much use for the
  client
* In the main loop, don't bother sleeping if it's going to be less than 10ms as
  the methods we're using to sleep at the moment aren't very precise
* Add Sys_PlatformInit for platform specific initialisation
* In win32 Sys_PlatformInit force selection of the DirectX SDL backend in order
  to get better fullscreen mouse input (in conjunction with a patched SDL DLL
  http://bugzilla.libsdl.org/show_bug.cgi?id=265)

code/qcommon/common.c

@@ -2864,7 +2864,14 @@ void Com_Frame( void ) {
 
 	msec = minMsec;
 	do {
-		Sys_Sleep( minMsec - msec );
+		int timeRemaining = minMsec - msec;
+
+		// The existing Sys_Sleep implementations aren't really
+		// precise enough to be of use beyond 100fps
+		// FIXME: implement a more precise sleep (RDTSC or something)
+		if( timeRemaining >= 10 )
+			Sys_Sleep( timeRemaining );
+
 		com_frameTime = Com_EventLoop();
 		if ( lastTime > com_frameTime ) {
 			lastTime = com_frameTime;		// possible on first frame