Catmull–Rom Splines

[mbostock]

I’d like to add Catmull–Rom spline interpolation, in particular the uniform (α = 0), centripetal (α = 0.5) and chordal (α = 1) variants. Note that interpolate("catmull-rom", 0) would be equivalent to interpolate("cardinal", 0), since both result in a uniform Catmull–Rom spline.

See also On the Parameterization of Catmull–Rom Curves by Yuksel et al.