[exercise-mainfile]

updated README

exercises/exercise-mainfile/README.md

@@ -45,41 +45,43 @@ The general structure of any main file in DuMux is:
 
 ```c++
 // define the type tag for this problem
-using TypeTag = TTAG(OnePCompressible);
+using TypeTag = Properties::TTag::OnePCompressible;
 ```
 The TypeTag is created in the `1pproblem.hh`. There you can see that it inherits from the __OneP__ and additionally from the __CCTpfaModel__ which defines the discretization method, which is in this case the cell-centered tpfa method.
 
 * a gridmanager tries to create the grid either from a grid file or the input file
 
 ```c++
-GridManager<typename GET_PROP_TYPE(TypeTag, Grid)> gridManager;
+GridManager<GetPropType<TypeTag, Properties::Grid>> gridManager;
 gridManager.init();
 ```
 * we create the finite volume grid geometry, the problem, solutionvector and the gridvariables and initialize them. Additionally we initialize the vtkoutput. Each model has a predefined model specific output with relevant parameters for that model.
 
 ```c++
 // create the finite volume grid geometry
-using FVGridGeometry = typename GET_PROP_TYPE(TypeTag, FVGridGeometry);
+using FVGridGeometry = GetPropType<TypeTag, Properties::FVGridGeometry>;
 auto fvGridGeometry = std::make_shared<FVGridGeometry>(leafGridView);
 fvGridGeometry->update();
 
 // the problem (initial and boundary conditions)
-using Problem = typename GET_PROP_TYPE(TypeTag, Problem);
+using Problem = GetPropType<TypeTag, Properties::Problem>;
 auto problem = std::make_shared<Problem>(fvGridGeometry);
 
 // the solution vector
-using SolutionVector = typename GET_PROP_TYPE(TypeTag, SolutionVector);
+using SolutionVector = GetPropType<TypeTag, Properties::SolutionVector>;
 SolutionVector x(fvGridGeometry->numDofs());
 
 // the grid variables
-using GridVariables = typename GET_PROP_TYPE(TypeTag, GridVariables);
+using GridVariables = GetPropType<TypeTag, Properties::GridVariables>;
 auto gridVariables = std::make_shared<GridVariables>(problem, fvGridGeometry);
 gridVariables->init(x);
 
 // initialize the vtk output module
-using VtkOutputFields = typename GET_PROP_TYPE(TypeTag, VtkOutputFields);
-VtkOutputModule<TypeTag> vtkWriter(*problem, *fvGridGeometry, *gridVariables, x, problem->name());
-VtkOutputFields::init(vtkWriter); //!< Add model specific output fields
+VtkOutputModule<GridVariables, SolutionVector> vtkWriter(*gridVariables, x, problem->name());
+using VelocityOutput = GetPropType<TypeTag, Properties::VelocityOutput>;
+vtkWriter.addVelocityOutput(std::make_shared<VelocityOutput>(*gridVariables));
+using IOFields = GetPropType<TypeTag, Properties::IOFields>;
+IOFields::initOutputModule(vtkWriter); //!< Add model specific output fields
 vtkWriter.write(0.0);
 ```
 
@@ -87,7 +89,7 @@ vtkWriter.write(0.0);
 
 ```c++
 // get some time loop parameters
-using Scalar = typename GET_PROP_TYPE(TypeTag, Scalar);
+using Scalar = GetPropType<TypeTag, Properties::Scalar>;
 auto tEnd = getParam<Scalar>("TimeLoop.TEnd");
 auto dt = getParam<Scalar>("TimeLoop.DtInitial");
 auto maxDt = getParam<Scalar>("TimeLoop.MaxTimeStepSize");