Golden Ball Source

A vtkGoldenBallSource algorithm has been added to provide a method to construct a solid, tetrahedralized ball. It uses a Fibonacci spiral (generated using the 「Golden Angle」 of π(sqrt(5) - 1)) which is then projected out of the plane onto a sphere and Delaunay-tetrahedralized into a ball. It includes a 「normal」 vector field by default which is zero-length at the center of the ball.

Besides the spiral construction this algorithm is also distinct from the existing sphere source because it produces a solid rather than a bounding surface.