(tramp-ftp-method): New user option.

(tramp-ftp-method): New user option.
(tramp-invoke-ange-ftp): New function to forward calls to
Ange-FTP.

(with-parsed-tramp-file-name): New macro for the usual big `let'
statement to dissect a file-name.

(tramp-handle-make-symbolic-link, tramp-handle-load)
(tramp-handle-file-name-directory)
(tramp-handle-file-name-nondirectory, tramp-handle-file-truename)
(tramp-handle-file-truename, tramp-handle-file-directory-p)
(tramp-handle-file-regular-p, tramp-handle-file-symlink-p)
(tramp-handle-file-writable-p, tramp-handle-file-writable-p):

Use the new macro and forward call to Ange-FTP if applicable.

(tramp-make-ange-ftp-file-name): New helper function to convert a
file name into an Ange-FTP file name, used by
`tramp-invoke-ange-ftp'.

(tramp-default-method-alist): New user option.
(tramp-find-default-method): Use it.

(tramp-sh-extra-args): New variable.
(tramp-find-shell): Use it.