Add ability to remove pairs of ghost vectors in LinearTransformationScene

[JasonGrace2282]

If one transformation is applied to self.plane, the plane is reset, and we want to show another transformation, the old ghost vectors from the first transformation will still remain.
If ghost vectors in LinearTransformationScene were, say lists of rules tuples, or possibly a VGroup, then it would allow us to write something like self.remove(self.ghostVectors[0]), and remove the first pair(s) of ghost vectors created.