implementation of file-related modules

[Ross Paterson]

On Wed, Oct 08, 2003 at 11:18:15PM -0400, Isaac Jones wrote:
> * I've noticed that System.Directory.renameFile behaves differently
>   between ghci, nhc, and hugs.  In particular, ghc is the only one who
>   complains when it's a directory.

This function is also Directory.renameFile, for which the Report agrees
with ghc (except for the exception thrown -- H98 has a limited choice).
Hugs will conform in future.

There's a minor bug in the GHC version: any errors are tagged with the
first argument (ditto for renameDirectory).