Separate Engine Service Functionality from Component

lib/service/engine_service.dart

@@ -5,7 +5,40 @@ import 'package:rules_of_living/src/Engine.dart';
 class EngineService {
   Engine _engine;
 
-  Engine get engine => _engine;
+  Engine get engine => _engine ?? create(null);
+
+  Engine create(html.CanvasElement canvas) {
+    _engine = Engine(canvas);
+    return _engine;
+  }
+
+  void run() {
+    engine.running = true;
+  }
+
+  void stop() {
+    engine.running = false;
+  }
+
+  void toggleRunning() {
+    engine.running = !engine.running;
+  }
+
+  void step() {
+    engine.step();
+  }
+
+  void reset() {
+    engine.reset();
+  }
+
+  void addRandomPattern() {
+    engine.running = false;
+    engine.addPattern();
+  }
+
+  void clear() {
+    engine.clear();
+  }
 
-  void create(html.CanvasElement canvas) => _engine = Engine(canvas);
 }