Implement mutations at reproduction #11
Description
When a new creature is born, currently it takes its neurons and connection from its both parents. We should implement neural mutations at this stage to ensure the "genetic" diversity among the population.
One way to do this would be to have a small chance of adding a new neuron to the pool of available neurons when creating connections. Or replace an existing connection to a random new one between two available neurons. Feel free to discuss your ideas about it in this issue.