Decrease use of the word "Emacsen" in docs

Decrease use of the word "Emacsen" in docs

"Emacsen" is either a less clear way of saying "old versions of
Emacs", or an implicit reference to XEmacs.  We recommend against
using it in the FAQ.  So use the more clear wording instead.

* doc/misc/gnus.texi (Oort Gnus):
* doc/misc/widget.texi (Basic Types, toggle):
* lisp/cedet/semantic/bovine/c.el (semantic-c-skip-conditional-section):
* lisp/cedet/semantic/wisent/comp.el (wisent-compile-grammar):
* lisp/desktop.el (desktop-save):
* lisp/erc/erc-compat.el:
* lisp/erc/erc-log.el:
* lisp/gnus/gnus-util.el (gnus-replace-in-string):
* lisp/mail/footnote.el:
* lisp/net/tramp-archive.el:
* lisp/net/tramp-smb.el:
* lisp/net/tramp-uu.el:
* lisp/net/tramp.el:
(with-tramp-locked-connection):
* lisp/org/ol-eww.el:
* lisp/org/org-compat.el:
(org-define-error):
* lisp/shadowfile.el:
* lisp/winner.el: Don't use the word "Emacsen".