Fix minStep checks for WolfeBacktracking

        /** Set the wolfe constants for Armijo and Wolfe condition (see class

          * description).

          * Assure that c1 < c2 < 1 and c1 in (0, 0.5).

          * @param c1 armijo constant

          * @param c2 wolfe constant */

        void setWolfeConstants(const Scalar c1, const Scalar c2)

            Index iterations = 0;

            while((maxIt_ == 0 || iterations < maxIt_) &&

                stepSize > minStep_ &&

                stepSize * decrease_ >= minStep_ &&

                !(armijoCondition && wolfeCondition))

            {

                stepSize = decrease_ * stepSize;