[Pharo-dev] Draw PolygonMorph with athens

for issue 13791 I uploaded a slice to make the PolygonMorph drawing work on an AthensCanvas. The results look great, although there is a small difference between athens and morphics curve polygon drawing. The difference is more visible for open curved polygons. I don't know why, I don't think we really need this :) and I would like to move on to work on some more important Morphs :) nicolai