The old animation was weird: it would reuse the labels
based on the index, not on the value. Thus, with the
new scaling code, sometimes there was no animation at all,
if the value, but not the position changed.
Consider the values instead and let labels appear/disappear.
This makes things slightly more complex.
While changing this code, create our own animation-class.
Thus, we can avoid having the dive axes being QObjects.
Signed-off-by: Berthold Stoeger <bstoeger@mail.tuwien.ac.at>