move declaration of variable 'averageInterface' into the fixed-point code

[[Imported from SVN: r6757]]

dirneucoupling.cc

@@ -356,8 +356,6 @@ int main (int argc, char *argv[]) try
         VectorType      oldSolution3d  = x3d;
         RodSolutionType oldSolutionRod = rodX;
         
-        RigidBodyMotion<3> averageInterface;
-
         if (ddType=="FixedPointIteration") {
 
             // //////////////////////////////////////////////////
@@ -428,6 +426,8 @@ int main (int argc, char *argv[]) try
             //   Extract new interface position and orientation
             // ///////////////////////////////////////////////////////////
 
+            RigidBodyMotion<3> averageInterface;
+
             computeAverageInterface(interfaceBoundary[toplevel], x3d, averageInterface);
 
         //averageInterface.r[0] = averageInterface.r[1] = 0;