[Dune] DoubleLinkedList in dune-common

[Christian Engwer]

> I'm, so to speak, totally against immediately removal of any file
> whatsoever. This will only cause trouble. I guess marking it deprecated
> should be sufficient.

For the normal user it would not be an immediat removal, as we would
mark it deprecated in 1.1.

> And by the way, the build system is not working
> since the last changes.

Works for me. Your comment is close to irrelevant. It does not help in
any way to fix the problem. It's hard to be less specific?
... perhaps something like "it's broken" would be good bug report?!

And by the way, could you answer my question?

Christian