* net/tramp.el (tramp-handle-set-file-times): Flush the file

* net/tramp.el (tramp-handle-set-file-times): Flush the file
properties.
(tramp-set-file-uid-gid, tramp-get-local-uid)
(tramp-get-local-gid): New defuns.
(tramp-handle-copy-file): Handle new parameter PRESERVE-UID-GID.
(tramp-do-copy-or-rename-file): New parameter PRESERVE-UID-GID.
Improve fast track.
(tramp-do-copy-or-rename-file-directly): Sync parameter list with
the other tramp-do-copy-or-rename-file-* functions.  Major
rewrite.
(tramp-handle-file-local-copy, tramp-handle-insert-file-contents)
(tramp-handle-write-region): Improve fast track.
(tramp-handle-file-remote-p): IDENTIFICATION can also be
'localname.
(tramp-maybe-open-connection): Let `process-adaptive-read-buffering'
be nil.