Add a setter for the verbosity member

dune/solvers/common/numproc.hh

@@ -22,6 +22,9 @@ class SolverError : public Dune::Exception {};
             : verbosity_(verbosity)
         {}
 
+        /** \brief Set the verbosity level */
+        void setVerbosity(VerbosityMode verbosity) {verbosity_ = verbosity;}
+
         /** \brief Controls the amount of screen output of a numproc */
         VerbosityMode verbosity_;