newton convergence writer: do not increment the time step index twice for each time step

git-svn-id: svn://svn.iws.uni-stuttgart.de/DUMUX/dumux/trunk@7792 2fb0f335-1f38-0410-981e-8018bf24f1b0

dumux/nonlinear/newtonconvergencewriter.hh

@@ -83,7 +83,6 @@ struct NewtonConvergenceWriter
 
     void endTimestep()
     {
-        ++timeStepIndex_;
         iteration_ = 0;
     };