Move Simulation Accesses to Simulation Class

Everything has been refactored away from engine, which now only controls updating & rendering within a specific timestep. (As well as stepping forward by calling a single update)

Everything regarding grids, patterns and cells has been moved into the simulation and the Services have been updated to reflect that.

lib/service/simulation_service.dart

@@ -2,35 +2,42 @@ import 'dart:html' as html;
 import 'dart:math';
 
 import 'package:rules_of_living/service/engine_service.dart';
+import 'package:rules_of_living/src/Simulation.dart';
 
 class SimulationService {
-  final EngineService _engine;
+  // DEFAULT VALUES
+  static final int DEFAULT_GRID_SIZE = 50;
 
-  SimulationService(this._engine);
+  final EngineService _engine;
+  final Simulation _sim = Simulation(DEFAULT_GRID_SIZE, DEFAULT_GRID_SIZE);
+
+  SimulationService(this._engine) {
+    _engine.simulation = _sim;
+    _sim.addRandomPattern(amount: 15, dispersal: 5);
+  }
 
   void reset() {
-    _engine.reset();
+    _sim.reset();
   }
 
   void addRandomPattern() {
-    _engine.addRandomPattern();
+    _sim.addRandomPattern();
   }
 
   void clear() {
-    _engine.clear();
+    _sim.reset();
   }
 
+  Point<int> get gridSize => _sim.gridSize;
   void set gridSize(Point<int> size) {
-    _engine.engine.gridSize = size;
+    _sim.gridSize = size;
   }
 
-  Point<int> get gridSize => _engine.engine.gridSize;
-
   //TODO split into RenderService when rendering is decoupled from engine.
   html.CanvasElement get canvas => _engine.engine.canvas;
   void set canvas(html.CanvasElement canvas) => _engine.engine.canvas = canvas;
 
   void toggleGrid() {
-    _engine.engine.toggleEdgeRendering();
+    _sim.renderEdges = !_sim.renderEdges;
   }
 }