PNGs were ran through TinyPng. Table.gif was weighing in at over 1.7mb
on my machine. Converted to webm and it's down to 80kb which is pretty
nice for something on the home page. Other gifs didn't have that much of
an improvement so I just left them as GIFs.
Fixes some tree rendering problems where lines were not properly drawn
at some levels during some circumstances.
* Change the API back to only allow one root.
* Now uses a stack based approach to rendering instead of recursion.
* Removes the need for measuring the whole tree in advance.
Leave this up to each child to render.
