robust 'flip y direction' for drawing to mplfig
Commit ee3b35bc fixed plotting on matplotlib figures when the extent was fitted to the vertex positions. I think the following is a more general solution:
- y.fa *= -1 - y.fa -= y.fa.min() + l, t, r, b = ctx.clip_extents() + y.fa = b + t - y.fa
This even worked for me when mplfig was a cartopy.mpl.geoaxes.GeoAxes instance.