[test][3pwateroil][implicit] Use NewtonSolver (fix docu)

test/porousmediumflow/3pwateroil/implicit/test_box3pwateroil.cc

@@ -180,7 +180,7 @@ int main(int argc, char** argv) try
         // report statistics of this time step
         timeLoop->reportTimeStep();
 
-        // set new dt as suggested by newton controller
+        // set new dt as suggested by the newton solver
         timeLoop->setTimeStepSize(nonLinearSolver.suggestTimeStepSize(timeLoop->timeStepSize()));
 
         // write vtk output