The ChFi3d_IsInFront code is currently not handling all the combinations
correctly. For example, if `if(fd1->IndexOfS2() == fd2->IndexOfS2())` is
true, it can happen that the `TopoDS::Face(DStr.Shape(fd1->Index(jf1)))`
returns a Face with entity == NULL. The subsequent usage of this NULL face
in `BRep_Tool::Parameters( Vtx, face )` will then cause a segfault.
While the best approach would be to identify the implementation bug in the
algorithm behind PChFi3d_IsInFron, a check + exception is used instead
because the actual algorithm is not known.
Signed-off-by: Charlemagne Lasse <charlemagnelasse@gmail.com>
1. Modify method IntPatch_ALineToWLine::MakeWLine: add correction of end points of each line on 2 surfaces if an end point is a pole on a surface.
2. Modify method IntPatch_WLine::ComputeVertexParameters: adjust a point on curve to corresponding vertex the following way: set 3D point as the point of the vertex and 2D points as the points of the point on curve.
