repl -convertargs enhancement

[David Levine]

Gone are the days of having to edit quoted-printable text when replying
using repl -convertargs:

commit 4bcc4ed6c68191eaf034a688424576e941acd66a
Author: David Levine <levinedl@acm.org>
Date:   Sun Mar 27 17:41:19 2022 -0400

    Allow editing of draft with repl -convertargs prior to encoding text.

Implmentation details, from the mhbuild(1) man page:

    If there are any Nmh-mhbuild- pseudoheaders in the composition
    file, mhbuild divides the translation into two stages.  The first
    stage includes all translations except encoding of text content.
    The second stage encodes text content as needed.  This allows the
    user to edit the text prior to encoding.  The second stage, along
    with the first stage if it had not yet been performed, is selected
    with the -auto switch.

David