Deoldify Vapoursynth filter

[Dan64]

I introduced the "auto" to help the beginners to assign a render_factor.
But this parameter is available only for ddcolor, also the calculated render_factor could impact significantly the speed.

In my opinion it could be removed.

In case you decide to add it, the calculated value should be visible in the render_factor box (gray-out) so that the user can see what render_factor is used.

The algo is the following

ddcolor_rf = min(max(math.trunc(0.4 * clip.width / 16), 16), 48)

Dan