Create a Box3d using left, right, bottom, top, front and back

Property definitions

geometry $ Box3d :: lrbtfb
	# Create a `Box3d` using left, right, bottom, top, front and back
	init lrbtfb(left, right, bottom, top, front, back: N)
	do
		lrbt(left, right, bottom, top)

		self.front = front
		self.back = back
	end
lib/geometry/boxes.nit:248,2--255,4