Things to add to the release notes for the next full release:

Backward incompatibilities:
- Changed exit status of each nmh command's -version and -help
  switches from 1 to 0.
- The following environment variables were deprecated in nmh 1.5
  and are removed from this release:
    MHPOPDEBUG (use -snoop command line switch instead)
    MM_NOASK (use -nolist and -nopause command line switches instead)
    NOMHNPROC (use -nocheckmime command line switch instead)
    FACEPROC (undocumented faceproc feature removed)
- Changed repl and dist default to -noatfile.  The default of -atfile
  was deprecated in nmh 1.5.  If there are no requests to maintain
  -atfile, it will be removed in the future.