Fix not carrying width and height in Simulation

lib/src/Simulation.dart

@@ -20,6 +20,9 @@ class Simulation {
   int _dispersal;
   CellPattern _pattern;
 
+  int get w => map.width;
+  int get h => map.height;
+
   Simulation(int w, int h) : this.map = new Grid.fill(w, h, _getGOLCell()) {
     print("Grid creation finished");
   }