Improvement: Keep annotations when simplifying mesh

[ChristianIngwersen]

I would love to see a new feature added to the blender_process.py script allowing you to take a big mesh with an *.eseg file and then returning a simplified mesh with new corresponding annotations

[ranahanocka]

As we discussed previously, I will add my MATLAB scripts (eventually...) to this repo which does that. But of course, I will accept a PR which does that within the blender script