Improve detection of start segments.
Improve detection of start segments.

Segments with multiple intersections need to be checked thoroughly to avoid errors.

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