Refactor sphere/torus generation.

Add:
	src/graphics/graphics.(c, h)
		-Remove superfluous variable declarations (holdovers from the time that
		point-coordinates were passed as individual arguments).

	src/graphics/matrix.(c, h)
		-Redefine `addSphere()`, `generateSphere()`, `addTorus()`,
		and `generateTorus()` with `Point_t *` parameters.