Should really handle remote links.

Traverse symlinks.

Mirror to non unix sites.

Implement mirror2 stuff (retry times, multiple sites with the same package...)

Need to edit symlinks so that you don't end up with symlinks pointing to nothing.
Also spot symlinks pointing to files that then get compressed!

Save all mail on a person-by-person basis and send at the end of an entire
run.

Mirror some dir' which is actually a symlink.  If this is replaced on
the remote machine by a real directory then the local symlink
has to be zapped before the make_dir will work.

I then want a control file:
        package site frequency overrides
Site is because the same package is often available at multiple sites.
The frequency is some way to control how often updates are attempted.
Overrides are just local changes to the information, so I could exclude
extra directories, turn off compression... without having to change the
basic package details.

Allow functions for file name conversions to be defined by the user.