Numeric Hessian; struggelig with convergence

Used the day to do the following:
- Design a numeric Hessian
- Realize the important fact that deepcopy() is needed in Julia if you
intend to copy something; otherwise, you'll end up with a new reference
to the same object in memory
- Struggle with the convergence. Thought that it was good, but realized
that most solutions were trivial ones.