Added temporary hack to force the Newton-Raphson algorithm used in GFace::XYZtoUV to enforce convergence in XYZ coordinates. Math should be checked for ruled surfaces obtained by extrusion, as some more fundamental problem seems to exists for points on the boundary of the CAD patches




git-svn-id: https://geuz.org/svn/gmsh/trunk@17527 59c8cabf-10d6-4a28-b43f-3936b85956c4