Some cleaning up

Added Population.size() and cleaned up the survivor selection.

src/survivor_selection/survivor_selection_methods.py

@@ -7,15 +7,6 @@ from initialization.chromosome_structure.chromosome import Chromosome
 class Survivor_Selection:
     """Survivor selection determines which individuals should be brought to the next generation"""
 
-    def remove_worst(ga, next_population):
-        """
-        Will bring all but the worst-performing chromosomes from the current generation.
-        The exact number of chromosomes removed depends on how many offspring were generated by parent selection.
-        """
-        iterator = 0
-        # While the size of the next population is less than it should be (as determined by the user)
-        while len(next_population.get_all_chromosomes()) < ga.population_size:
-            # Add the best chromosome from the current population that hasn't already been brought over
-            next_population.add_chromosome(ga.population.get_all_chromosomes()[iterator])
-            iterator += 1
-        return next_population
+    def fill_in_best(ga, next_population):
+        """Fills in the next population with the best chromosomes from the last population until the population size is met."""
+        return ga.population[:ga.population_size-next_population.size()] + next_population