technique similar to the new MCAA.
This new technique simplifies the code significantly by unifying lines,
curves, and transformed curves. Blog posts forthcoming.
This removes a whole lot of code from `pathfinder_path_utils`. Hopefully
the remaining code can go upstream.
These changes regress quality of stroke widths for cubic curves, because
they move fill-to-stroke conversion before cubic-to-quadratic
conversion. To fix that, we will need to recursively subdivide when
doing fill-to-stroke conversion.
Patrick Walton