The new option EMPTY_DIRECTORIES_ONLY will make delete() only delete
empty directories. Any attempt to delete files will fail. Can be
combined with RECURSIVE to wipe out entire tree structures and
IGNORE_ERRORS to silently ignore any files or non-empty directories.
Change-Id: Icaa9a30e5302ee5c0ba23daad11c7b93e26b7445
Signed-off-by: Robin Stocker <robin@nibor.org>