Partially sync files.el from XEmacs 21.5 for wildcard support.

Partially sync files.el from XEmacs 21.5 for wildcard support.

This changeset partially syncs files.el with XEmacs 21.5 (cb65bfaf7110
tip) to give #'find-file and friends support for wildcards.

With this, you can do things like: `C-x C-f /path/to/*.c' and all .c files
in /path/to/ will be opened.  Oh, and it also means that the current
ispell XEmacs package will work again.

	* lisp/files.el (find-directory-functions): New.
	(switch-to-next-buffer): New.
	(switch-to-previous-buffer): New.
	(switch-to-next-buffer-in-group): New and fixed to not use
	obsolete vars.
	(switch-to-previous-buffer-in-group): New. and fixed to not use
	obsolete vars.
	(find-file-create-switch-thunk): New.
	(find-file): Synched up with XEmacs 21.5
	cb65bfaf7110 tip.
	(find-file-wildcards): New.
	(find-file-suppress-same-file-warnings): New.
	(find-file-noselect): Synched up with XEmacs 21.5 cb65bfaf7110
	tip.
	(find-file-noselect-1): New.
	(insert-file-literally): New.
	(find-file-literally): New.
	(file-expand-wildcards): New.
	(shell-quote-wildcard-pattern): New.

Signed-off-by: Steve Youngs <steve@sxemacs.org>