#5 Headers/body out sync if multiple access

[Mike Kienenberger]

If Popover is being used on two separate machines (or
probably if any other access to your pop account is
being used), and a second client deletes a message,
then Popover (the first client) gets out of sync and starts
associating the message headers with the wrong
message bodies, probably due to header caching.
Some way is needed for Popover to detect that things
are out of sync and correct the problem.

V2.0 (v150) for windows (via WO 5.0)