[ESS] elisp code: show function arguments

[Sven Hartenstein]

Dear friends of Emacs and R,

I wrote an emacs lisp function that shows a R-function's arguments and
their default values on a single keystroke or as you type the opening
paranthesis ("(") after a function name. People like me who can't
remember all the parameter's names can thus very easily see them.

See screenshots and get it here:
http://www.svenhartenstein.de/emacs-ess.php

The function uses ESS functions. I consider it quite handy and would
be interested to know whether anything similar existed already and how
it could be improved in case someone else considers it useful. (This
is one of my first lisp functions, I'm sure there's much to optimize.)
In fact, any feedback is highly appreciated.

Happy R-coding,

Sven