Unify examples structure (#1118)

* Animations, CameraAndViewport, CollisionDetection and Components unified

* Added descriptions to effects

* Rename input games

* Unify input stories

* Add info to parallax section

* Added descriptions to the rendering examples

* Add descriptions to the sprites directory

* Fix utils and rendering section

* Add descriptions to the widgets section

* Delete directory that rebase brought back

* Unify game names

* Added some styleguide docs for examples

* Fix analyze issues

* All files should have _example as suffix

* Made the FollowComponentExample a bit easier to understand

* Change priority of ember

examples/lib/stories/utils/timer_example.dart

@@ -0,0 +1,55 @@
+import 'package:flame/game.dart';
+import 'package:flame/input.dart';
+import 'package:flame/timer.dart';
+import 'package:flutter/material.dart';
+
+class TimerExample extends FlameGame with TapDetector {
+  static const String description = '''
+    This example shows how to use the `Timer`.\n\n
+    Tap down to start the countdown timer, it will then count to 5 and then stop
+    until you tap the canvas again and it restarts.
+  ''';
+
+  final TextPaint textConfig = TextPaint(
+    style: const TextStyle(color: Colors.white, fontSize: 20),
+  );
+  late Timer countdown;
+  late Timer interval;
+
+  int elapsedSecs = 0;
+
+  @override
+  Future<void> onLoad() async {
+    await super.onLoad();
+    countdown = Timer(5);
+    interval = Timer(
+      1,
+      onTick: () => elapsedSecs += 1,
+      repeat: true,
+    );
+    interval.start();
+  }
+
+  @override
+  void onTapDown(_) {
+    countdown.start();
+  }
+
+  @override
+  void update(double dt) {
+    super.update(dt);
+    countdown.update(dt);
+    interval.update(dt);
+  }
+
+  @override
+  void render(Canvas canvas) {
+    super.render(canvas);
+    textConfig.render(
+      canvas,
+      'Countdown: ${countdown.current.toStringAsPrecision(3)}',
+      Vector2(30, 100),
+    );
+    textConfig.render(canvas, 'Elapsed time: $elapsedSecs', Vector2(30, 130));
+  }
+}