=============================================== Issue description: https://forum.freecad.org/viewtopic.php?f=3&t=70325 https://github.com/FreeCAD/FreeCAD/issues/7520 The general algorithm to calculate normals miserably fails when the curve is a line segment and the point through which the normal to a curve is to be drawn is colinear with the line segment. The solution is to provide specific code for this corner case. fixes #7520