Lennart Regebro <regebro@gmail.com>, Original Author

Justin Gruenberg implemented the Quadradic Bezier calculations and
provided suggestions and feedback about the d() function.

Michiel Schallig suggested calculating length by recursive straight-line
approximations, which enables you to choose between accuracy or speed.
Steve Schwarz added an error argument to make that choice an argument.

ClayJarCom speeded up `point()` calculations for paths.

Thanks also to bug fixers Martin R, abcjjy, Daniel Stender, MTician, 
blokhin and jaraco.
