Extract EngineService into separate service

lib/components/controls_component.dart

@@ -1,6 +1,6 @@
 import 'package:angular/angular.dart';
 import 'package:angular_components/angular_components.dart';
-import 'package:rules_of_living/service/engine_service.dart';
+import 'package:rules_of_living/service/control_service.dart';
 
 @Component(
   selector: 'sim-controls',
@@ -15,27 +15,27 @@ import 'package:rules_of_living/service/engine_service.dart';
   styleUrls: const ["controls_component.css"],
 )
 class ControlsComponent {
-  final EngineService engine;
+  final ControlService ctrl;
 
-  ControlsComponent(this.engine);
+  ControlsComponent(this.ctrl);
 
   void onStartClicked() {
-    engine.toggleRunning();
+    ctrl.toggleRunning();
   }
 
   void onStepClicked() {
-    engine.step();
+    ctrl.step();
   }
 
   void onResetClicked() {
-    engine.reset();
+    ctrl.reset();
   }
 
   void onRandomClicked() {
-    engine.addRandomPattern();
+    ctrl.addRandomPattern();
   }
 
   void onClearClicked() {
-    engine.clear();
+    ctrl.clear();
   }
 }

lib/components/simulation_component.dart

@@ -1,7 +1,7 @@
 import 'dart:html' as html;
 
 import 'package:angular/angular.dart';
-import 'package:rules_of_living/service/engine_service.dart';
+import 'package:rules_of_living/service/control_service.dart';
 
 @Component(
   selector: 'gol-simulation',
@@ -10,9 +10,9 @@ import 'package:rules_of_living/service/engine_service.dart';
   providers: [],
 )
 class SimulationComponent implements OnInit {
-  final EngineService engineService;
+  final ControlService ctrl;
 
-  SimulationComponent(this.engineService);
+  SimulationComponent(this.ctrl);
 
   @override
   void ngOnInit() {
@@ -29,6 +29,6 @@ class SimulationComponent implements OnInit {
     
     the canvas did not load correctly :(
     ''', canvas.width / 2 - 50, canvas.height / 2);
-    engineService.canvas = canvas;
+    ctrl.canvas = canvas;
   }
 }