Population.update_fitness now uses multithreading.Pool if there is one

manduca/Population.py

@@ -180,4 +180,13 @@ class EvolutionSimulator(object):
 
    def update_fitness(self):
       all_manducas = self.population + self._children + self._mutants
-      [manduca.fitness for manduca in all_manducas]
+      if self.pool is not None:
+          # Don't bother sending manducas that already have _fitness saved
+          all_manducas = filter(lambda m: m._fitness is None, all_manducas)
+          for idx, fitness in enumerate(self.pool.map(compute_fitness, all_manducas)):
+             all_manducas[idx]._fitness = fitness
+      else:
+          [manduca.fitness for manduca in all_manducas]
+
+def compute_fitness(manduca):
+    return manduca.fitness