[Fluxus] commit: extrusions

[Dave Griffiths]

Hi all,

I've added an attempt at a decent system for modelling using extrusion
of profiles along paths. This shapes can also be animated in order to
grow the shape along the path in time. More info and an animation here:

http://www.pawfal.org/dave/blog/2009/07/extrusions-revisited/

There is also a new example - extrusion.scm
The code for this is in poly-tools.ss

cheers,

dave