Modify update_iter()

[Balaji Pokuri]

iter_max is used only as a check in update_iter(). This makes the variable redundant. Instead, update_iter() can be modified to take in a number, of iterations. This will make the optimization cleanly serial, also enabling the user to give different kappa strategies in different iteration stages.

[Balaji Pokuri]

Resolved in eb18954.

TODO: add example that uses it.