For "git status" and the diff family the submodule.*.ignore settings from
.git/config and .gitmodules can be used to override the default set via
diff.ignoreSubmodules on a per-submodule basis. Let's do this consistently
and teach checkout to use these settings too.
Signed-off-by: Jens Lehmann <Jens.Lehmann@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>