This patch refactors the calls to the dune-istl solvers.
The SeqScalarProduct, and SequentialInformation is now explicitly
constructed and later used to construct the smoothers
generically. Aditionally the linear operator (MatrixAdapter) is
constructed before calling the various solver dependent solve
routines.
While this does not change the behaviour of the code it is a
preparatory step to support parallel solvers. These parallel
solvers only differ in the type of the scalarproduct and
linear operator used from the sequential ones.
