* net/tramp.el (top): Remove `tramp-rfn-eshadow-update-overlay'

* net/tramp.el (top): Remove `tramp-rfn-eshadow-update-overlay'
from `rfn-eshadow-update-overlay-hook' when unloading.
(tramp-methods): Add `tramp-copy-keep-tmpfile' for "rsync" and
"rsyncc".  Adjust doc string.
(tramp-temp-buffer-file-name) New buffer-local defvar.
(tramp-handle-insert-file-contents, tramp-handle-write-region):
Keep temporary file when indicated by method ("rsync" and
"rsyncc").
(tramp-handle-write-region): Handle APPEND.
(tramp-delete-temp-file-function): New defun.  Added to
`kill-buffer-hook'.