Always check that residual is ok for explicit stepping (even non-paranoid)
Move ode problem class to its own header
Add unsteady heat problem to micromag library header
Add max steps option in command line args
In MyDocInfo class just store string of args not a pointer (simpler)
In jacobians self test don't compare info files
Initial commit of general purpose driver code

Idea is to be able to work with ALL problem types (at least problems for
which we are just doing a newton solve or timestepping) in one driver.

So far it only works with ode problems, but the framework is there.

Other additions needed for this:

* Add is_steady() function to MyProblem

* Add InitialConditionFctPt and generic set_initial_condition

* Make ode exact functions compatible with new initial condition function