When collecting the points to build plane use the points on the curve instead of poles (in case of BSpline and Bezier curves).
Side effect changes:
Changes in Geom2dHatch_Elements are to increase the chance of correct 2d classification (by the means of Geom2dHatch_Classifier) by taking more than just one point on the edge to construct the classification ray and by checking if this ray is not tangent to the edge itself.