[dune-pdelab] The Dune book and the dune-pdelab Context branch

[Oliver Sander]

Dear pdelab team,

as you may be happy to hear, my book on Dune is now very close
to completion.  With the exception of the chapter on dune-pdelab,
the entire text is written and only needs a bit more polishing
and proof-reading here and there.

The chapter on dune-pdelab is also almost finished.  In the generic
Springer book style it is currently about 90 pages long, and contains
several full examples.  It needs a bit more writing, but most of it
is there already.

In agreement with Steffen I wrote the dune-pdelab chapter such that
it describes the Context branch

  https://gitlab.dune-project.org/pdelab/dune-pdelab/merge_requests/388

which is a rewrite of the LocalOperator interface, in the
PDELab::Experimental namespace.  I consider this rewrite a considerable
improvement over the current interface.

Steffen has been very helpful in fixing various bugs that I found
while adapting my example programs, and all of them work very well
now.  However, even though this has been promised many times,
the rewrite is still not in the git master of dune-pdelab yet.
This blocks the completion of my book, as I am not willing to spend
more time on text describing code that is not in master.  On the
other hand, I am equally unwilling to go back to describing the
old LocalOperator interface, because the Context-one is just so
much better.

Therefore, in order to finish the book, I see myself forced to
completely remove the chapter on dune-pdelab on friday, Oct 25,
unless the Context branch has been merged into git master by that date.
That will be a loss for everyone involved, but I cannot wait any longer.
On the other hand, I still hope that we can find a positive solution.

Best regards,
Oliver

PS: For the case that the dune-pdelab chapter should be kept, any work on

  https://gitlab.dune-project.org/pdelab/dune-pdelab/merge_requests/429
  https://gitlab.dune-project.org/pdelab/dune-pdelab/issues/133
  https://gitlab.dune-project.org/pdelab/dune-pdelab/issues/131

would be much appreciated, but is not blocking.