#3 use subdirs in recursive archiving

[Terry Brown]

a modifcation of the -f behavior so that mail from

~/mail/personal/parties/halloween

goes in

~/old_mail/personal/parties/halloween.archived

instead of

~/old_mail/personal-parties-halloween.archived

which would basically require a 'mkdir -p' type
function to ensure the destination directory exists.

Cheers -Terry