Support remote editing in emacsclient via Tramp

Support remote editing in emacsclient via Tramp

* lib-src/emacsclient.c (main, decode_options)
(print_help_and_exit, longopts): New option '--tramp' / '-T' which
specifies how emacs should use tramp to find remote files.

* doc/emacs/misc.texi (TCP Emacs server): New subsection describing
the various knobs to tune server.el for TCP opereation.
(emacsclient Options): Reference "TCP Emacs server" from description of
--server-file.  Document the new '--tramp' / '-T' options.
* doc/emacs/emacs.texi (Top): Update the top-level menu.

* etc/NEWS: Mention the new option.