[Dune] unreached headers in DUNE

[Oliver Sander]

>>
>> IMHO Removing unreached headers might be dangerous.
> I agree. I was not suggesting to remove them without any further
> consideration. I only wanted to mention that there are files which are
> not being tested in the core modules themselves. If you are fine with
> that, I am totally happy for you. IMHO of course.
>

You are right.  Any API file provided by a module should be tested
in that module, even if not used anywhere else.  I am afraid though
that I cannot say here much more than 'patches are welcome'.

cheers,
Oliver

> Kind regards
> Bernd
>