Parallel text view

[Benjamin Fallenstein <b.fallenstein@xxxxxx>]

Hi all--

I've just comitted a first version of a parallel text view, which shows
three text vstreams (Y dimension) connected (X dimension) -- that is,
the accursed vstream, the vstream of the cell left of the accursed cell,
and the vstream of the cell right of the accursed cell. It's not perfect
(the looks need to be tuned, and connections to non-shown cells aren't
drawn yet), but it is *definitely* worth looking at. (Or so I think.)

-b. :)