gradients for fluxus

create a list of gradient steps, then use vgradient instead of a spagethi of nested vlerps :)

example code

(require "gradient.ss")

(define grad (list 
				(gradient-step 0   (vector 1 0 0))
				(gradient-step 0.5 (vector 0 1 0))
				(gradient-step 1   (vector 0 0 1))))

(for ((p (in-range 0 1 0.05)))
	(with-state
		(translate (vector (* 20.0 (- p 0.5)) 0 0))
		(colour (vgradient p grad))
		(build-cube)))