[ESS] Combining sweave and pdflatex into one helper function

[Stephen Eglen]

>   ess-error: ESS process not ready. Finish your command before trying
>   again.

that mighte indicate its trying to run the 2nd commmand before the 1st
has finished.  try the following:

  (defun edd-sweave ()
    "Run sweave and pdflatex"
    (interactive)
    (ess-swv-weave) ; this should make no difference to what you had
    (sleep-for 30)  ; wait 30 seconds ...
    ;;(ess-swv-latex)  ;; is this needed? if the next line runs pdflatex?
    (ess-swv-PDF "pdflatex")
  )