Do not hard-code BitSetVector as the default bitvector type

dune/solvers/solvers/iterativesolver.hh

@@ -5,6 +5,7 @@
 
 #include <dune/common/ftraits.hh>
 
+#include <dune/solvers/common/defaultbitvector.hh>
 #include <dune/solvers/solvers/solver.hh>
 #include <dune/solvers/iterationsteps/iterationstep.hh>
 #include <dune/solvers/norms/norm.hh>
@@ -14,7 +15,7 @@ namespace Dune {
   namespace Solvers {
 
     /** \brief Abstract base class for iterative solvers */
-    template <class VectorType, class BitVectorType = Dune::BitSetVector<VectorType::block_type::dimension> >
+    template <class VectorType, class BitVectorType = DefaultBitVector_t<VectorType> >
     class IterativeSolver : public Solver
     {
         // For norms and convergence rates