[mpfa][localassemblerbase] define interface with zero threshold

dumux/discretization/cellcentered/mpfa/localassemblerbase.hh

@@ -57,9 +57,11 @@ class InteractionVolumeAssemblerBase
     using Problem = P;
     using FVElementGeometry = EG;
     using ElementVolumeVariables = EV;
-
     using Helper = InteractionVolumeAssemblerHelper;
 
+    template< class IV >
+    using Scalar = typename IV::Traits::MatVecTraits::FaceVector::value_type;
+
  public:
     /*!
      * \brief The constructor.
@@ -97,7 +99,7 @@ class InteractionVolumeAssemblerBase
      * \param getT Lambda to evaluate the scv-wise tensors
      */
     template< class DataHandle, class IV, class TensorFunc >
-    void assembleMatrices(DataHandle& handle, IV& iv, const TensorFunc& getT)
+    void assembleMatrices(DataHandle& handle, IV& iv, const TensorFunc& getT, Scalar<IV> wijZeroThresh = 0.0)
     {
         DUNE_THROW(Dune::NotImplemented, "Implementation does not provide a assembleMatrices() function");
     }