Extra interactions options

[Masboes]

Originally suggested by @S4K4YUME in #162

An idea for an additional mode code be:

1. Get boundingbox for root
2. Treewalk until the algorithm is at the leaves
3. Use boundingboxes of leaves to calculate an all encompassing boundingbox which includes the root and all leaves
   3b. optionally we might need some padding
4. Pan + zoom to show the full subtree on the canvas

Another idea, align the rotation of the view with the rotation of the root of the subtree.