Close small holes in mask

[MartinKlevs]

The full meet model often leaves small holes in my face. It could be worthwile to add an optional hole filling step.

[floe]

This is already happening here: https://github.com/floe/deepbacksub/blob/main/deepseg.cc#L303-L306 Probably needs a bit of tweaking on size of info.element...

[BenBE]

I think the intention was to close all internal holes, not just the small stuff near the edges.

[floe]

Hm, I had considered finding the outer contour and filling everything inside, but that would fail with e.g. raised arm touching the head?

[BenBE]

Good point …