Fix tearing in short-lived dynamic lights at high FPS

[Calinou]

The tearing occurred because the dynamic light was shown for a single frame, but when running above the monitor refresh rate, less than a single frame was actually visible on screen. Even when V-Sync was used, the dynamic light was visible for a very small portion of time on screen depending on the monitor refresh rate.

The fix works by ensuring each dynamic light is visible for at least 32 milliseconds, which roughly matches the appearance of dynamic lights as they were in vanilla Quake 2 on period-appropriate hardware (running at 30-35 FPS).

Moving dynamic lights (e.g. from rockets) are not impacted by this change - they still move as smoothly as before.

This uses the same fix as Yamagi Quake 2.

• This closes remove tearing on muzzleflashes? #321.

Preview

Game is running at 1,000 FPS (60 FPS video):

q2pro_dynamic_light.mp4

[skullernet]

Muzzleflash dynamic lights are always shown for at least 16 msec in Q2PRO, which corresponds to 60 FPS. This can be raised to 32 msec but in comparison to 16 I don't see much difference in terms of tearing. Tearing is a result of having vsync disabled, you can't avoid it without vsync. The sample video is pretty much useless here since tearing can only be seen on your monitor.