Break scene.transforms into subpackage

Just reorganization. All scene/visual examples work as previously.
Ready for review.
And actually now that I think about it, the standard way we've solved circular import problems is by nesting the offending import, so we should probably move this to the `__rmul__` def. I don't think it will hurt performance since they should all end up imported at the same time anyway, but it makes it clearer what's going on from a code perspective.