[multidomain]

- removed Beavers-Joseph dependency for the handling of the
couplingInflow and couplingOutflow boundaries
- removed todo and unused lines of code
- updated reference solutions for the multidomain problem (only small
deviations from reference)

reviewed by gruenich, bernd



git-svn-id: svn://svn.iws.uni-stuttgart.de/DUMUX/dumux/trunk@14102 2fb0f335-1f38-0410-981e-8018bf24f1b0