Interval Propagation Method

[Tarocca]

A lonely TODO wait for his programmer savior within slicingmodel.jl It seems to be about adding interval propagation.

On the same file, there seems to be a performance issue with the optimisation method "evaluate!" as it may be a bit slow. It could be replaced by Bayesian optimisation but that needs Gaussian Processes to be implemented first.

[FriesischScott]

Ultimately, we will allow the user to specify the interval propagation method to use. Currently all we have is global optimization which is very inefficient.