[ESS] Introducing Polymode

[Vitalie Spinu]

Hi All, 

I would like to announce a development version of new multi-major-mode
called polymode. Source, screenshots and installation instructions are
here:
   
   https://github.com/vitoshka/polymode


There is still some work to be done as it is not very stable as yet. I
have just realized that I won't be able to pursue very active
development for the weeks to come, so I decided to announce it right
away. This includes some indentation issues and unstable font-lock in
C++ submodes. C++R seems to work fine.

Currently it has builtin supports for Rnw, Rmd, Rhtml, Rbrew, Rcpp, cppR
and "live" R examples in Rd and ess-help buffers. Adding new polymodes
is literally about 25 lines of declarations. See "modes" directory and
particularly poly-R.el. Also look in test directory for test
examples. The interface is not fully settled as yet and thus, not
documented.

There is also a default association with md extension. This basically
means that as long as you have a proper declaration ```foo, and foo-mode
function exists the chunk will be initialized with that mode.

It would be really nice if enthusiastic people can try it out and report
bugs/comments/suggestions, either directly to me, or preferably on the
github bug tracker. But please read the words warning first;)

Hopefully it will be useful to some people even at this stage.

    Vitalie