[Mimedefang] base64 to quoted-printable

[Michael Fox]

> On Tue, 10 Oct 2017 16:11:07 -0400
> Joseph Brennan <brennan at columbia.edu> wrote:
> 
> > On Tue, Oct 10, 2017 at 1:48 PM, Michael Fox <news at mefox.org> wrote:
> > > I need to convert base64 to something readable.
> 
> > To be honest I can't think of a reason to do this. 

Nevertheless, I need to for an old client.

So, back to my question:

if ($bh = $entity->bodyhandle) ;

    $qp_body = encode_qp($bh->as_string)

}

It seems to work (I use md_syslog() to show the first 20 chars).  Is that
right?  Or is there a better way? 

Then, I see an action_change_header(), but no action_change_body().  So,
presume I need to build a new entity by copying headers from the old entity,
replacing the Content-Transfer-Encoding header, and replacing the body.
Then use replace_entire_message().

Does that sound about right?

Michael