In batch mode allow missing expect and input files.

For batched unit tests, we can't predict which cases
use input redirections and which have verification (expect)
data, so don't redirect input if an implicit input file
doesn't exist, and don't try to check output against a
non-existant expect file.

Start to make the coded embedded in tutorials at least pass
the checks. Many examples could have expects but don't.
Some will require rewriting to support verification,
and some just to allow a build.