Add types where possible

[Rezenders]

Running the planner with the current pddl formulation for SUAVEsuave takes around 0.5 seconds. I believe this can be improved with a better typing system by adding specialized types for the objects, e.g., fd_recover_thrusters - function_design and so on.

Also, PlanSys is taking very long to solve all the derived predicates (around 30 seconds) due to my poor implementation of supporting existential preconditions and derived predicates. I believe this could be greatly improved if objects and constants had more specialized types that are not subtypes of each other, i.e., part of another type hierarchy.

@tobiaswjohn do you think you could do such modifications the owl->pddl tool?

[tobiaswjohn]

I think there are two views on this issue:

1. technically, it is not a big problem to introduce such types. BUT
2. this results in not interpreting the axioms in the ontology as usual, i.e. we use OWL as a modelling language without using the OWL interpretation. I've seen this a couple of times and I think it makes it really hard for others to understand what we do.

I propose to focus on removing the unnecessary derived predicates (i.e. most of them) first (see issue #19) and see what the difference is before adding more types is a non-owl-conformant way.