* lisp/Makefile.in (install): Use the lisp function `dgnushack-exported-files'.

* lisp/Makefile.in (install): Use the lisp function `dgnushack-exported-files'.

* lisp/nnmail.el (nnmail-pathname-coding-system): Default to `binary'.
* lisp/nnheader.el (nnheader-pathname-coding-system): Ditto.

* lisp/message.el (message-get-reply-headers): Remove useless `concat'.

* lisp/md5.el: Restore the file.

* lisp/dgnushack.el (dgnushack-compile): Refer to the constant
`dgnushack-exported-files'.
(dgnushack-exported-files): New function.
(dgnushack-exported-files): New constant.
(dgnushack-unexported-files): Add some files.
(dgnushack-tool-files): Remove, merge it into `dgnushack-unexported-files'.

* lisp/base64.el: New file -- base64 encoding functions using MEL.