Remove instance creator functionality

[stefan-lindegger]

Instance creator has no dependency to strategy pattern and implementation.
It is rather misleading and should be moved to BBT.StructureTools repository.

[marco-bertschi]

We should think about moving it to it's own repository - It's a dependency of the structure tools, not an integral functional part.
There are other candidates like that in the StructureTools Repository - For example the various extension methods. We should move all of this into a separate repository were we can maintain commonly used functionalities.