Remove several references to Emacs 22 and earlier

Remove several references to Emacs 22 and earlier

* admin/charsets/mapfiles/README:
* doc/emacs/custom.texi (Saving Customizations):
* doc/lispintro/emacs-lisp-intro.texi (Simple Extension):
* doc/misc/efaq-w32.texi (Location of init file):
* doc/misc/gnus-faq.texi (FAQ 1-3):
* doc/misc/gnus.texi (Top, Various, Image Enhancements):
* lisp/erc/erc-menu.el (menu):
* lisp/progmodes/cfengine.el (cfengine-fill-paragraph):
Remove some references to Emacs 22 and earlier.

* doc/lispref/buffers.texi:
* doc/lispref/eval.texi:
* doc/lispref/files.texi:
* doc/lispref/keymaps.texi:
* doc/lispref/loading.texi:
* doc/lispref/minibuf.texi:
* doc/lispref/positions.texi:
* doc/lispref/variables.texi: Remove comments about "Emacs 19
specific" features.