Move sha1.el and hex-util.el from lisp/gnus/ to lisp/net/ (was: Re: Moving files from lisp/gnus/ to lisp/net/?)

[Simon Josefsson <jas@extundo.com>]

The first file is sha1.el.  It is an implementation of an algorithm
very similar to MD5, which is part of Emacs (in C).  It is generally
useful, and not Gnus specific in any way.  The API is stable, the only
API change that I can locate, since the file was created in 1999, was
a new optional parameter to some functions.

The file sha1.el needs hex-util.el, which is a small file to hex
encode strings.  It is similar to base64-*.  If it is possible to do
the same using other functions in Emacs, that may be better.  Please
look at the file and tell.  But it is a small files, that could be
useful elsewhere as well.

Both can be documented in LispRef, it seems.  For SHA1, I can copy the
MD5 node, and for hex-util, I can create something inspired by the
base64 node.

Alternatively, the functions could be documented in emacs-mime.texi's
"Basic Functions".  It document many similar packages already.  I
suggested documenting the new mail-utils functions, proposed in
another thread, in the same manual.  The name "Emacs-MIME" is
confusing though, "Emacs Lisp Mail Handling" or similar would be more
appropriate.

Documenting Mail Handling related functions in emacs-mime.texi instead
of lispref might be good if people think lispref is too large.  I
suspect people interested in mail utilities will be able to find a
different manual.  There could be links from lispref to emacs-mime as
well.