New Environment and Individual objects. Design consideration: models are associated with specific objects and events. Hence existing models cannot be directly used with new objects. Either existing models need to be extended to work with new objects, or new models should be created to work with new objects. For example, PopulationModel can be individual independent, but because IndividualShell is not an Individual a new interface was necessary to be able to handle IndividualShell objects. Additionally, this commit also changed the object configuration layout
Initial reproducing individual model. population of 50 was dead after 134 years, assuming a female can only reproduce once.