Deoldify Vapoursynth filter

[Dan64]

In order to fix the problems related to AverageFrame.

I'm planning to:

1) limit to 11 frames the max number of frames to be used in the average
2) enable only "central" average because left/right are complementary
3) introduce a weighted average where the near frames have an higher weight.

Here an example with 11 frames

https://imgsli.com/MjQ5Mzc3

This should almost fix the observed problems.

Dan