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/parallax/advanced_parallax_example.dart

@@ -0,0 +1,35 @@
+import 'package:flame/components.dart';
+import 'package:flame/game.dart';
+import 'package:flame/parallax.dart';
+
+class AdvancedParallaxExample extends FlameGame {
+  static const String description = '''
+    Shows how to create a parallax with different velocity deltas on each layer.
+  ''';
+
+  final _layersMeta = {
+    'parallax/bg.png': 1.0,
+    'parallax/mountain-far.png': 1.5,
+    'parallax/mountains.png': 2.3,
+    'parallax/trees.png': 3.8,
+    'parallax/foreground-trees.png': 6.6,
+  };
+
+  @override
+  Future<void> onLoad() async {
+    await super.onLoad();
+    final layers = _layersMeta.entries.map(
+      (e) => loadParallaxLayer(
+        ParallaxImageData(e.key),
+        velocityMultiplier: Vector2(e.value, 1.0),
+      ),
+    );
+    final parallax = ParallaxComponent(
+      parallax: Parallax(
+        await Future.wait(layers),
+        baseVelocity: Vector2(20, 0),
+      ),
+    );
+    add(parallax);
+  }
+}