phylo tree div renderer

I just rebased my stuff on top of the last kltm/bbop-js commit.  Hopefully that makes this pull request just a simple git fast-forward; let me know if it doesn't apply cleanly.

I moved the phylo div renderer to widget and renamed/renamespaced it, and moved the development scaffolding to _scratch.  I've left in my work-in-progress tree/matrix combination (in _scratch) for now.