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... 
Perhaps the wrapper could check the shape and only pad if necessary?