v0.13.0 Population simulator

A first version of a population simulator has been developed. Rather than having a very artificial variation in the number of individuals, here each person is managed from birth to death. At first, I didn't think I would need so much detail. It is the future management of the assignment of individuals in companies and services based on their level of education that motivated me to do it. We probably won't see people wandering the streets, but that doesn't stop me from trying to give them substance. However, individuals will have a more abstract influence than the characters, another key feature of the game.