* NURBS sweep API.

* Nurbs Sweep node: initial implementation.

* Fixes.

* Transformation API for Nurbs curves.

* Remove debug print.

* Interpolation support.

Side effect: nurbs transparency support for "Iso U/V" node

* Some code documentation.

* minor fixes.

* Support iso_curve() for FreeCAD Nurbs surfaces.

* minor fix.

* Documentation for the "Nurbs Sweep" node.

* Node icon.