[Rd] wishlist: better error message in R CMD check

[Gabor Grothendieck]

I was running R CMD check on Windows XP 2.0.1beta and 
got this:

Error in parse(file, n, text, prompt) : syntax error on 602

After a lot of aggravation I finally discovered that if I did
this:

copy *.R allofthem.R

and checked line 602 in allofthem.R that I could find the error.
I noticed that there are repeated references in the help archives
to this sort of error and how hard it is to locate it.  It 
certainly would be nice to tell the user which file the error
is in and to point to the original files, not some intermediate
file or if one must do it in terms of intermediate files to keep
the file around and tell the user which and where it is.