woow!
This a great new addition!! I was longing for Spiro curves!
Thanks a lot.

Btw: if I am not wrong, Spiro are naturally arc-length parametrized... It could be worth defining a new pattern-along path stuff with the skeleton being a Spiro curve.
I wrote the 2geom code for the arc-length parametrization of bezier curves, and this is a delicate point, that still needs to be improved (in particular to handle cusps in a better way)...
Does some bezier to Spiro converter exist somewhere? (respecting the shape of the curve, I mean). A robust one would be interesting with this respect...

Spiro curve are so nice. Thank's again.
jfb.