TODO

Rename scale() to resize() and add scale() that uses transform scale
Docs: start() and end()
Rename circle.radius to diameter? Change toPolygon so they don't double in size
Change draw event to update event in doc
Cache .length() on Polygon and Path if object did not call changed()

Backlog

Ability to add custom attributes to any shape
Clipping path support
mouse events should work on individual shapes
Polygon intersects() http://bjornharrtell.github.io/jsts/
Polygon intersection() http://bjornharrtell.github.io/jsts/
Polygon difference() http://bjornharrtell.github.io/jsts/
Polygon union() http://bjornharrtell.github.io/jsts/
Polygon symdifference() http://bjornharrtell.github.io/jsts/
Text layout with bounds, lineHeight, etc
Filters
Blend modes
masking
Gradients
textWidth()
keypressed
requestAnimationFrame should work in node
Debug should have full polygon vectors and anchor vectors
Ability to set debug line color and debug circle color