Add animation while inserting or remvoving a node

[The4Summers]

It would be nice to be able to configure an animation when inserting a new node under a node that is already expanded, or when removing a node from a parent. This is one of the nice thing they have implemented in the animated_tree_view library!
Also, when expanding/collapsing a parent node with children, it would be nice to implement various types of animations. Again, the expansion animation implemented in the animated_tree_view library is nice. Don'T worry, everything else is better in this fancy_tree_view library, I still prefer using it than the other just mentionned! ;-)