Compecon

--Fix bug in hessian function, which would fail to compute the Hessian if evaluation
point was int (instead of float).
--hessian and jacobian can take lists of numbers as evaluation points; they will
be converted to numpy arrays.
--Simplified notation in implementation of golden search method.
--Added Gauss-Jacobi and Gauss-Seidel solvers for linear equations.

--Changed "print=" keyword to "show=" in several solvers. This is to avoid
confusion with the python "print" reserved keyword. As of this version, using
the old keyword will raise a warning. Future version will raise an error.

--Added an option to demo.savefig to specified file formats