C2d

see documentation: https://github.com/Flamenco/jsPDF/wiki/c2d-Plugin
see test page at: http://htmlpreview.github.io/?https://github.com/Flamenco/jsPDF/blob/c2d/test/test_context2d.html

Notable new features include arcs, stroked text, text baselines, and context stacks.

I feel that by standardizing the API via this interface, more users will be able to understand the usage, convert existing HTML5 canvas code to vector based PDFs, and save time by not requiring the developers to write documentation :)

This is far from complete, but still quite useful.
Is this needed? I mean, perhaps `strokeOption = ''` is enough?

Well, if it's to clear a previous set stroke state, i'd use an internal flag and only set `0 tr` when `flags.stroke` is no longer set (?)