This is an implementation of the scanline edge-flag algorithm for
antialiased path filling described here:
https://mlab.taik.fi/~kkallio/antialiasing/EdgeFlagAA.pdf
The initial implementation does not try to implement every possible
optimization in favour of keeping things simple. However, it does
support:
- Both evenodd and nonzero fill rules
- Applying paint styles/gradients
- A range of samples per pixel (8, 16, 32)
- Very nice antialiasing :^)
This replaces the previous path filling code, that only really applied
antialiasing in the x-axis.
There's some very nice improvements around the web with this change,
especially for small icons. Strokes are still a bit wonky, as they don't
yet use this rasterizer, but I think it should be possible to convert
them to do so.
