Particle fade timing fix

[mankrip]

[Baker]

Interesting stuff.

I've mostly avoided the particle system except for Nehahra compatibility and giving WinQuake some of the FitzQuake adjustments for particles (separating rendering from physics mostly).

And I guess I needed to play with particle sizing in Mark V's software renderer because the particles would get too big at higher resolutions.

[mankrip]

My code in this tutorial isn't good enough either, but I've decided to post it as soon as possible, to avoid the risk of forgetting how to explain these quirks of the vanilla renderer.

Afterwards I've refined and rewritten all these changes in a more proper way, but I can't post it right now because my main laptop's PSU is busted.

Anyway, vore trails' particles should also be taken care of, and there's no need to subtract 0.01f from cl.time when setting the particle to be removed on the next frame; p->die = cl.time; is enough.