RMAIL mbox development

[Chong Yidong]

Per RMS's request, we're going to try to include Rmail-mbox in Emacs 23.
It may not be ready in time for the feature freeze, but we'll make a
special exception for it.  In other words, the new Rmail features may be
added to the trunk during the bug-fixing/pretest period.

Paul Michael Reilly <address@hidden> has been working on the Rmail-mbox
code, but he needs help.  If you have the time to work on this, please
email him.