Handling of Boundaries with RectangularBoundariesTransformation in optimser

[alisterde]

I was having a go with these and noticed you can use both in one optimiser with different boundaries.

I'm not sure what we want to do about this but we probably don't want people using them both in one optimiser, as you may not end up exploring the entire desired region if you pass the optimser a different boundary in as a RectangularBoundariesTransformation and boundaries.