An archetype is used for creating new entities. It contains one or many
definitions for entities, along with relationship between them. It also
contains any extra data needed for a world simultion, such as thoughts
and knowledge.
Archetypes should be seen as blueprints for entity types, as they
describe how new one should be composed. They are created just as
regular entities, using the existing Create op functionality.
As an example, there should be one "human" entity type, with archetypes
such as "settler", "merchant", "soldier" etc. This differs from the
current setup where each of these are separate entity types.
The code would segfault if installing a new entity class failed at the last
stage in Inheritance. Inheritance would return null, which would be assigned
to the factory's m_type. addProperties() assumes the pointer is not null.
This fix adds a check, and reports a failure undoing the whole process.
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 is the second step in cleaning up a rather messy call path
which was different when installing the classes a game actually uses
from the data files from the base rules that are common to all.
