All IG code should use the interface of LocatedEntity when dealing
with any entity, rather than sometimes requiring Entity. Add virtual
functions to the interface where required, and modify all other interfaces
to stop them using Entity. This makes the code way cleaner, and much better
de-coupled.
This means we have changed the code to use our shape classes to store the
data, and modified the expected Atlas format to match the more standard
way of expressing shapes in Atlas which the shape classes expect.
