Figure out whether or not to keep tree plugin

[scottjehl]

good for nested lists, but simple lists of links behave in a similar way, with a lot less code. Maybe we don't need tree, or if we keep it, it'd be better if the leaf nodes end up going to a new page rather than loading it into the UL structure.

[scottjehl]

John's tree chunker workaround, based on Doug's Idea for splitting a tree into separate pages:
http://jsbin.com/enofu3/2/edit