Topic/plat 6723

The method getModifiedCurvatureMatrix in NonLinearLeastSquare and NonLinearLeastSquareWithPenalty was slow because it computed J^T * J (where J is the Jacobian matrix) directly calling the getEntry method of DoubleMatrix2D. We now have a dedicated method in MatrixAlgebra that works directly on double arrays.
Perhaps fill with e.g. NaN so if there's an exception thrown and caught at least the error is clearly nonsense?