AAMs problems in Refactor branch

[jalabort]

On the refactor branch #67 all AAM fitting algorithms using the LucasKanadeStandardInterface are slightly wrong. At the moment they are performing additive, instead of compositional updates!

We have to options to amend this:

1. Re-implement the solve_all_map and solve_all_ml methods on the previous interface so that they effectively use the "parameter Jacobian" Jp. This might make the functions _solve_all_map and _solve_all_ml quite complicated...
2. Go back to using the VComposable interface. This would mean that PDMs need to support the previous interface and that ModelDrivenTransforms and PDMs need to handle priors internally.

[patricksnape]

In Option 1 - how complicated? I think I prefer option 1. Even if there are basically two subfunctions that do either additive or compositional updates?