name-rev: deprecate --stdin in favor of --annotate-stdin

name-rev: deprecate --stdin in favor of --annotate-stdin

Introduce a --annotate-stdin that is functionally equivalent of --stdin.
--stdin does not behave as --stdin in other subcommands, such as
pack-objects whereby it takes one argument per line. Since --stdin can
be a confusing and misleading name, rename it to --annotate-stdin.

This change adds a warning to --stdin warning that it will be removed in
the future.

Signed-off-by: "John Cai" <johncai86@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>