This is a library which lays out trees and can animate changes from tree to
tree.  It can handle it if you make things not a tree, but be sure not to use
any functions which only make sense in a tree context, such as depth().  

We have three sample visualizations, and you can see any of them by simply
downloading the .jar file in this directory and double-clicking it.  To
download it, click the file name, and then click "View Raw" at the bottom of
the page.