allow the "last_msg" value to be changed as well.
When dumping a msgbase index, show 'M' for messages (not blank).
When running maintenance, read the entire index in one shot.
Don't display progress (percentage counting) during maintenance (just
slows it down).
When reading messages, get the plain-text version (MIME decode if needed).
When a message base fails to open, continue processing additional message bases
if specified on the command-line.