(ange-ftp-expand-file-name): Set default to

(ange-ftp-expand-file-name): Set default to
default-directory if nil.  Check whether default starts with a
drive specifier on windows-nt, as well as name, and call real
function if so.  Remove code to strip prefix before // or /~ since
`expand-file-name' itself no longer does that.
(ange-ftp-expand-dir): Use `grep-null-device' instead of
"/dev/null", which is incorrect on windows-nt.
(ange-ftp-file-name-all-completions): Fix root directory regexp for windows-nt.
(ange-ftp-start-process): On windows-nt, always send a "help foo"
command to ensure the ftp process produces some output, and force
the process to use raw-text-dos decoding.
(ange-ftp-canonize-filename): On windows-nt, strip drive specifier
from expanded remote name.
(ange-ftp-write-region): Allow binary transfer on windows-nt if
remote host type is unix.  Ensure `last-coding-system-used' is
given an appropriate value, so that basic-save-buffer isn't
confused by the coding used with the ftp process.
(ange-ftp-insert-file-contents): Ditto.
(ange-ftp-copy-file-internal): Ditto.
(ange-ftp-real-expand-file-name): Use standard definition on windows-nt.
(ange-ftp-real-expand-file-name-actual): Remove obsolete function.
(ange-ftp-disable-netrc-security-check): Make default value be t on windows-nt.

(ange-ftp-start-process): Undo previous change.