PGA-4: Enable choosing whether or not to elite members in the selection process

[gnypit]

• create a parameter taken by the GeneticAlgorithm class to specify the way elite chromosome behave during the selection stage;
• enable at least two options: (1) elite chromosomes do not tak part in selection, they are simply copy-pasted into the new generation and (2) the elite chromosomes take part in the selection process apart from being copy-pasted.