Show centiseconds for best time trial times (if available)

Since VVVVVV 2.3, time trial best times are stored not just with the
number of seconds, but also the number of frames. However, there was
no room to display it with the old design of the time trials screen.
Now there is, so it can easily be displayed now with a small change!

Unset frames are stored as -1, which fits perfectly into the frames
argument of help.format_time(), because in that case the amount of
centiseconds is not shown.

It should be noted that opening VVVVVV 2.2 will instantly wipe your
frames records, as described by #1030. But many people will likely
never open 2.2 anymore.

desktop_version/src/Render.cpp

@@ -1588,9 +1588,10 @@ static void menurender(void)
                 label_len = SDL_max(label_len, font::len(0, label));
                 font::print(0, 32, 65+sp*3, label, tr, tg, tb);
 
-                font::print(0, label_len+48, 65+sp, game.timetstring(game.besttimes[id_trial]), tr, tg, tb);
-
                 char buffer[SCREEN_WIDTH_CHARS + 1];
+                help.format_time(buffer, sizeof(buffer), game.besttimes[id_trial], game.bestframes[id_trial], true);
+                font::print(0, label_len+48, 65+sp, buffer, tr, tg, tb);
+
                 vformat_buf(
                     buffer, sizeof(buffer),
                     loc::gettext("{n_trinkets}/{max_trinkets}"),