cardinal(pt1: Vec2 , m1: Vec2 , m2: Vec2 , pt2: Vec2 , tension: number ): Vec2
A second order function returning an evaluator for the given 2D Cardinal curve
parampt1- Previous point
paramm1- First point
paramm2- Second point
parampt2- Next point
paramtensionThe tension of the curve, [0..1] from round to tight.
returnsA function which gives the value on the 2D Cardinal curve at t