Rename App to Engine

lib/app_component.dart

@@ -1,7 +1,7 @@
 import 'package:angular/angular.dart';
 
 import 'dart:html' as html;
-import 'package:rules_of_living/src/App.dart';
+import 'package:rules_of_living/src/Engine.dart';
 
 @Component(
     selector: 'my-app',
@@ -10,7 +10,7 @@ import 'package:rules_of_living/src/App.dart';
 class AppComponent implements OnInit {
   var name = "World";
 
-  App engine;
+  Engine engine;
 
   @ViewChild("caCanvas")
   html.CanvasElement canvas;
@@ -24,7 +24,7 @@ class AppComponent implements OnInit {
     If you see this 
     the app is broken :(
     ''', canvas.width/2, canvas.height/2);
-    engine = new App(canvas);
+    engine = new Engine(canvas);
 
     html.window.animationFrame.then(animFrame);
   }

lib/src/Engine.dart

@@ -2,7 +2,7 @@ import 'dart:html' as html;
 
 import 'package:rules_of_living/src/Grid.dart';
 
-class App {
+class Engine {
   // Elapsed Time Counter - useful for Safety Timeout
   Stopwatch _elapsed = new Stopwatch();
 
@@ -22,7 +22,7 @@ class App {
   Grid grid = new Grid(100, 100);
   bool running = false;
 
-  App(this.canvas) {
+  Engine(this.canvas) {
     _elapsed.start();
     grid.addPattern(amount: 15, dispersal: 5);
   }