[BROKEN] cleanups that get the code closer to running again
[STILL BROKEN] repair ..getitem.. (it actually never worked)

R uses symbols (a la lisp) for its funky slicing tricks. I don't know how to make symbols,
 so I use inventedthe convention that NA means "ignored"
[SORTA FIXED] plot.densities now works as it used to again.

I am very happy with where this is going. I just hope I can finish it in time to write the report.
factor our marginal.title()

(also scratches elsewhere; i'll fix  them in a moment)
[UNTESTED] port ks.tests to marginals_do; kill crufty old code

This has a behaviour change: the old code only observed the upper triangle of V; this does the whole thing
 *shrug*