Just so we’re clear, this doesn’t do anything yet. I have never written anything in C or C++, so I just want to do something simple to learn it.
This will, eventually, become a simplified (that is, more sane) Vapoursynth port of https://github.com/Zeght/Morefun/blob/master/fixborders.avsi, written as a plugin because that just seems like the more sensible choice.
No go away and do something else. There is nothing to see here (yet).