Feature Req: add file export functionality

[virtualritz]

It would be especially useful to have support for exporting to Wavefront OBJ, OpenNURBS or IGES.

Unbeknownst to most people, OBJ has (trimmed) NURBS support which is natively understood by e.g. Autodesk Maya or Rhinoceros3D. See e.g. Paul Bourke's website for a format description including these features.

That way the library can be used to generate procedural geometry for such applications.