Function  
 bezier
(pt1: Vec2, pt2: Vec2, pt3: Vec2, pt4: Vec2): (t: number) => Vec2A second order function returning an evaluator for the given 2D quadratic Bezier curve
param pt1- First point
param pt2- First control point
param pt3- Second control point
param pt4- Second point
returns A function which gives the value on the 2D quadratic Bezier curve at t
 
 