preconditioner, i.e. set new linearization point.

exported and used on Python side for RungeKutta solvers such that these
can be used in parallel.

function. This now works after mem leak in discrete function has been
fixed.

  consequently use operators *= etc on discrete function.

to not be available.

full,expl, and impl so that something reasonable is returned also when using the
IMEX RK scheme - of course operator.explicitOperator.dtEstimate also provides this
information...

Dune::Fem::Parameter class

experiment with scalling limiter in chemical reaction

the improved "testing" function back to testing.py