Tree Visualization of the notebook

So, I just said that I was not going to put hours into developing a tree visualization of the notebook.

Today I changed my mind, I played a little bit with some numbers and ended up with something that I kind of like.

The tree button is enabled in the action bar (bottom right) and shows a node graph of your notebook, which slowly tries to minimize distance between conected nodes. 

Some bugs might appear, but with my current notebook is working properly.

See you soon!