implemented the applicative functor for cubes
fixed bugs in cube size code
made shift operations be transformations on cubes...but i could still probably use one that forgets the old cube, and returns me an entirely new cube that just looks at the 'shifted cube'.

fixed the move command in world edit
finally using scalacheck generators for cubes, and added lots of nice commutativity tests, and other tests.
also added one simple test for the cube applicative, but there needs to be more.