BUG: integrate: Fix some bugs and documentation errors in the ode solvers.

This pull request continues https://github.com/scipy/scipy/pull/3206.  Specifically, it fixes the handling of banded Jacobians in the `vode` solver and in the `complex_ode` class, and fixes some documentation mistakes.
> I wonder if anyone uses this code... 

I don't know, but if anyone has tried, they probably gave up in frustration.

I'll add a check so that the wrapper is only used if `self.ml > 0`.