[ESS] Upgraded ess and need to specify correct file in .emacs

[Rich Shepard]

   I have upgraded ess and now all files are in /usr/share/emacs/ess/ rather than
/usr/local/share/emacs/ess/. I use only R, no commercial (or other)
statistial software. Which of the files in that sub-directory do I specify
in ~/.emacs so the text editor finds ess without complaining?

   Here's the list of r-specific files:

ess-r-args.el
ess-r-args.elc
ess-r-d.el
ess-r-d.elc

   There are, of course, many others.

TIA,

Rich