- boxdarcyfluxvariables: access function to velocity without all the upstream...

- boxdarcyfluxvariables: access function to velocity without all the upstream weighting decisions . 

- boxdarcyfluxvariables: access function to velocity (Vector). 

- boxdarcyfluxvariables: upstream decision based on kGrdpNormal instead of velocity

- boxdarcyfluxvariables: (correctly) rename velocity to volume flux (also in the models that are already restructured)

- mpnc model & test: use the new velocity calculation

- update the reference solution (actually the change in the reference was due to a change in order of multiplication in the residual that could not be avoided). 

- increased the LinearSolver.ResidualReduction to 1e-11 (i.e. until the solution does not change any more)

- (the old velocity calculation and the new one give the identical result with LinearSolver.ResidualReductionsolver set to 1e-11 for both cases)


git-svn-id: svn://svn.iws.uni-stuttgart.de/DUMUX/dumux/trunk@8758 2fb0f335-1f38-0410-981e-8018bf24f1b0