[Dune] release

[Andreas Dedner]

Dear Dune Developers,

the last two weeks have seem more activity in all core modules than we 
have had
for quite a lot of time. The commits I had to make this weekend to fix 
things that
got broken due to these changes show that the code is not yet very stable.
Some of them where due to my lack of testing some to others - who cares.

I just wanted to suggest a freeze for the trunk as well, at least for the
next two weeks. I hope this will make the backporting simpler for the 
release
managers and will simplify finding bugs in the code or build system for all
of us.

Greetings
Andreas