Position aware stackBox animators

[uwerat]

The current implementation of QskStackBoxAnimator does not care about the position of the items in the stack box.

While this is often the intended behavior we might also have situations, where the animator should traverse over the other items in between. We would need to offer a mode, so that the application developer can control the behavior.

Now when flipping from position 1 to position 4 we would do this in 3 turns ( 1-> 2 -> 3 -> 4 ) for the position aware mode, while we would do only 1 turn ( 1-> 4 ) for the other mode.