* Use Sys_Sleep to limit FPS, which will save CPU

* Add com_maxfpsUnfocused and com_maxfpsMinimized; self explanatory
* Fix reopening of bug 3703, I hope

code/sys/sys_win32.c

@@ -519,6 +519,9 @@ Block execution for msec or until input is recieved.
 */
 void Sys_Sleep( int msec )
 {
+	if( msec == 0 )
+		return;
+
 	if( msec < 0 )
 		WaitForSingleObject( GetStdHandle( STD_INPUT_HANDLE ), INFINITE );
 	else