[glyf2] outside overlaps

[davelab6]

The fact that variable fonts cannot have outside overlaps is the bane of my existence

— https://twitter.com/DaytonaMess/status/1691762455179862455

If we are going to do glyf 2 like cff2, maybe we can fix this too

[anthrotype]

What is an "outside overlap"? Are you referring to that thing in Glyphs.app where relatively small self-intersecting portions of a contour that appear to be on the "outside" of the main contour and would otherwise render as little triangles get instead clipped away following some arbitrary rule that has nothing to do with the standard nonzero winding rule used everywhere else to fill contours with black? I can see how it might be useful while designing but I think it diverges to much from the way outlines are understood in general and in fonts in particular.