convexHull
Computes the convex hull of this polygon's vertices using the Quickhull2 algorithm.
The resulting polygon's vertices are in counterclockwise winding order. A polygon cannot represent a hull with fewer than three unique, non-collinear points, so this function throws IllegalArgumentException for duplicate-only, two-point, or collinear input.
Return
A new Polygon2 representing the convex hull of this polygon's vertices.
Throws
if the hull is degenerate.