[rmail-mbox-branch]: expunge

[Alfred M. Szmidt]

Okie, this is *really* annoying, rmail expunges messages WITHOUT
asking me.  I can't see how I didn't notice this eariler....

rmail-confirm-expunge's value is y-or-n-p

And another thing, when you open a RMAIL mbox with find-file, it
doesn't change to rmail-mode automaticly; since Emacs doesn't see any
magic that makes it change into the correct mode.

[I wouldn't recommened merging this back into trunk by a long shot, it
 is far to broken]

Happy hacking (and any appologise if this mail sounds harsh, but I
really wasn't that happy when RMAIL deleted mail without asking me!).