Parametric curves

[Ottia Tuota]

I updated the plugin. It now accepts python lists in the GUI for the custom parameter values. The old format is also accepted. I also updated the documentation file doc.pdf acordingly. The text in the GUI is changed for the custom values. The new version 0.9.3 is in the same place where the old was.

The spiral in Ofnuts' post #11 now looks as follows, when run up to 20*pi:

   

All further comments are very welcome.