Generalized extrusion along a path

I just opened a similar issue to this against OpenSCAD itself (https://github.com/openscad/openscad/issues/114), but it applies equally well here.

It would be nice if one could extrude a two-dimensional figure along a path. This would allow the user to specify a path (a series of points or perhaps even a more sophisticated path representation), a 2d figure, and perhaps a basis set to construct the product space of these two spaces. Clearly this is not a trivial request, but it should be recorded nevertheless.

This could be a nice differentiating factor for ImplicitCAD if it is implemented here first. It doesn't seem like it would be too difficult to do this in the implicit function representation.