Added logging for CMessage::get_body().

  This is part of #148.
  Correctly handle decoding message bodies.

  This updates #148.
  Consolidated UTF-conversion code.

  This avoids duplication and updates #148.
  Get the value of sendmail_path() after the on_sent_message hook.

  Previously we  ran:

   1.  get the sendmail_path.
   2.  Call the on_sent_message hook.
   3.  Send the mail, using the value of sendmail from 1.

  We (obviously) should get the sendmail_path after calling the
 hook to cope with users who change it there.

  Closes #149.
  Updated the logging message.
  Resync against the code that lumail-uses.

  That means our test/utility code & application will show the
 same results.
  New release imminent.

  Tonight :)