printmatrix now appears in the doxygen documentation

[[Imported from SVN: r1158]]

istl/io.hh

@@ -161,6 +161,7 @@ namespace Dune {
     }
   }
 
+  /** \brief Prints a generic block matrix */
   template<class M>
   void printmatrix (std::ostream& s, const M& A, std::string title, std::string rowtext,
                     int width=10, int precision=2)