added two use cases to **more than an editor

I added two use cases of which people may be unaware.  ESS provides a powerful front-end to the popular statistics language R.  R's own editor is terrible as many new students find out the hard way.  ESS does everything R studio can do plus a whole lot more.  Also, IPython is a very popular REPL within the Python community that was significantly enhanced by web client 2 years ago. The Emacs IPython notebook integrates that with a much richer set of editing features.