It's very hacky, and it needs lots of work, but it seems to have converted
Peter's "syslinux" archive successfully. Whether the end result is correct
or not is to be seen.
Tons of work still to do: do name conversion properly, and do tags etc.
And testing. Lots of testing.
I looked a bit at my old BK tools for the same thing, but they were
just so horrid in many ways that I largely rewrote it all and these
tools do things a bit differently. Instead of aggressively piping
data from one process to another (which was clever but very hard
to follow), this first just splits out the mbox into many smaller
email files, and then does some scripts on these temporary files.