Resolution-Independent Vector Fonts

for rendering with for unlimited scaling in WebGL

See #4746

![screenshot 2014-05-03 19 13 14](https://cloud.githubusercontent.com/assets/314997/2870220/9404344e-d2b4-11e3-9988-f4f36c7632a8.png)
(left is default triangulation, center is gpu hardware accelerated font rendering, right is wireframe for toggling between non-bezier subsets and convex hall).

Caveats:
- currently support shapes with only lines and quadratic bezier curves