sw/src/game.cpp:RunLevel: Call faketimerhandler in a loop, based on code

from EDuke32-OldMP. Main difference from EDuke32-OldMP is that this is
done even while staying in the menu; Behaviors will otherwise break.
We should also call timerUpdateClock() before the loop, especially
after removing the call to this function from faketimerhandler soon.

source/sw/src/game.cpp

@@ -2599,6 +2599,10 @@ void RunLevel(void)
             ExitLevel = FALSE;
             break;
         }
+
+        timerUpdateClock();
+        while (ready2send && (totalclock >= ototalclock + synctics))
+            faketimerhandler();
     }
 
     ready2send = 0;