more working on the configuration API.

Renderers will be a map of datatype -> renderer. This leaves the
computing of datatype up to the user. The other option would be to allow
users to specify a function that would compute the datatype. This
doesn't seem like the right move though. Too complex.
is this something that i can work with?
back to confusion.

need to actually start doing some visualizing with d3 to see how this
would work. Walking the line between doing nothing and doing too much.
Need to slice things the right way.