[ESS] Snw files are not weaved by C-c C-c from AucTeX-mode

[Rodney Sparapani]

A.J. Rossini wrote:
> Because those were hacks that Fritz introduced for some reason (I
> don't really know why, and I don't have an opinion as to their
> goodness), where as the standard Noweb format is the traditional
>
> << >>=
>
> @
>
> encoding.  It's not really robust, either, but there are cool
> noweb-related toys for formatting and indexing that you can use by
> using this.
>
<SNIP>

I think hack is a little strong.  Code marks that are valid latex
are the only kind that make any sense.  That way, you can still make a
valid document if you don't have the statistical package installed
(or emacs or ESS for that matter).

Furthermore, this shows us the way to extend to other packages.
Right now, <<>>= and @ don't tell you which package that you
need to run: R, S+, SAS?  It's a minefield.  But, if we
introduce the other environments as needed, then we have a system
that can be rationally extended as necessary.  For example, the
following environments:  Rinput, S+input, SASinput, etc.

Rodney