Improve Curve#getParameterOf() to better handle very small curves.
Improve Curve#getParameterOf() to better handle very small curves.

See #799

lehni/paper.js,byte-foundry/paper.js,lehni/paper.js,iconexperience/paper.js,lehni/paper.js,byte-foundry/paper.js,byte-foundry/paper.js,iconexperience/paper.js,iconexperience/paper.js