Add inhibit-remote-files and without-remote-files

Add inhibit-remote-files and without-remote-files

* doc/emacs/files.texi (Remote Files): Do not document tramp-mode
any longer.  Describe inhibit-remote-files instead.

* doc/lispref/files.texi (Magic File Names): Add without-remote-files.

* doc/misc/tramp.texi (Frequently Asked Questions): Do not
document tramp-mode any longer.  Describe inhibit-remote-files and
without-remote-files instead.

* etc/NEWS: Add inhibit-remote-files and without-remote-files.
Fix typos.

* lisp/net/tramp.el (inhibit-remote-files): New defun.
(without-remote-files): New defmacro.

* test/lisp/net/tramp-archive-tests.el
(tramp-archive-test49-without-remote-files):
* test/lisp/net/tramp-tests.el (tramp-test49-without-remote-files):
New tests.
(tramp-test50-unload): Rename.