Add support for quad curves in font writing

[aui]

trueType use toBuffer () and download () method error.

BUG DEMO:

http://aui.github.io/demo/opentype.js/readwrite-ttf.html

[fdb]

Hi,

Thanks for the bug report. The error shows that quad curves are currently not supported.

A workaround is to use only fonts with bézier curves – that is, fonts that use CFF outlines. I know that's not always an option.

I'll add support for quad curves soon.

[aui]

Thank you for your work, I'm looking forward to this feature!

[zswang]

from https://raw.githubusercontent.com/DmitryBaranovskiy/raphael/master/raphael.js

 q2c = function (x1, y1, ax, ay, x2, y2) {
            var _13 = 1 / 3,
                _23 = 2 / 3;
            return [
                    _13 * x1 + _23 * ax,
                    _13 * y1 + _23 * ay,
                    _13 * x2 + _23 * ax,
                    _13 * y2 + _23 * ay,
                    x2,
                    y2
                ];
        }

[fdb]

This is fixed with #86, thanks @zswang!