Make computeAveragePressure take the centerOfTorque as a FieldVector.

It was a RigidBodyMotion before, but the rotation part of that was
ignored.  Semantically it is just a position, hence a FieldVector
is better.

[[Imported from SVN: r6598]]

dirneucoupling.cc

@@ -392,7 +392,7 @@ int main (int argc, char *argv[]) try
             // Using that index 0 is always the left boundary for a uniformly refined OneDGrid
             computeAveragePressure<GridType::LevelGridView>(resultantForce, resultantTorque, 
                                               interfaceBoundary[grid.maxLevel()], 
-                                              rodX[0],
+                                              rodX[0].r,
                                               neumannValues);
 
             rhs3d = 0;
@@ -520,7 +520,7 @@ int main (int argc, char *argv[]) try
                 // Using that index 0 is always the left boundary for a uniformly refined OneDGrid
                 computeAveragePressure<GridType::LevelGridView>(resultantForce, resultantTorque, 
                                               interfaceBoundary[grid.maxLevel()], 
-                                              rodX[0],
+                                              rodX[0].r,
                                               neumannValues);
 
                 rhs3d = 0;

dune/gfe/averageinterface.hh

@@ -472,7 +472,7 @@ template <class GridView>
 void computeAveragePressure(const Dune::FieldVector<double,GridView::dimension>& resultantForce,
                             const Dune::FieldVector<double,GridView::dimension>& resultantTorque,
                             const BoundaryPatchBase<GridView>& interface,
-                            const RigidBodyMotion<3>& crossSection,
+                            const Dune::FieldVector<double,GridView::dimension>& centerOfTorque,
                             Dune::BlockVector<Dune::FieldVector<double, GridView::dimension> >& pressure)
 {
     const GridView& gridView                    = interface.gridView();
@@ -567,7 +567,7 @@ void computeAveragePressure(const Dune::FieldVector<double,GridView::dimension>&
                         phi_i[j] = shapeFunctionValues[i];
                         
                         mu_tilde[i][j].axpy(quad[qp].weight() * integrationElement,
-                                            crossProduct(Dune::FieldVector<double,dim>(worldPos-crossSection.r), phi_i));
+                                            crossProduct(Dune::FieldVector<double,dim>(worldPos-centerOfTorque), phi_i));
 
                     }
                     
@@ -653,7 +653,7 @@ void computeAveragePressure(const Dune::FieldVector<double,GridView::dimension>&
 
     Dune::FieldVector<double,3> outputForce(0), outputTorque(0);
 
-    computeTotalForceAndTorque(interface, pressure, crossSection.r, outputForce, outputTorque);
+    computeTotalForceAndTorque(interface, pressure, centerOfTorque, outputForce, outputTorque);
 
     outputForce  -= resultantForce;
     outputTorque -= resultantTorque;