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/collision_detection/circles_example.dart

@@ -0,0 +1,78 @@
+import 'dart:ui';
+
+import 'package:flame/components.dart';
+import 'package:flame/extensions.dart';
+import 'package:flame/game.dart';
+import 'package:flame/geometry.dart';
+import 'package:flame/input.dart';
+import 'package:flutter/material.dart' hide Image, Draggable;
+
+class CirclesExample extends FlameGame with HasCollidables, TapDetector {
+  static const description = '''
+    This example will create a circle every time you tap on the screen. It will
+    have the initial velocity towards the center of the screen and if it touches
+    another circle both of them will change color.
+  ''';
+
+  @override
+  Future<void> onLoad() async {
+    super.onLoad();
+    add(ScreenCollidable());
+  }
+
+  @override
+  void onTapDown(TapDownInfo info) {
+    add(MyCollidable(info.eventPosition.game));
+  }
+}
+
+class MyCollidable extends PositionComponent
+    with HasGameRef<CirclesExample>, HasHitboxes, Collidable {
+  late Vector2 velocity;
+  final _collisionColor = Colors.amber;
+  final _defaultColor = Colors.cyan;
+  bool _isWallHit = false;
+  bool _isCollision = false;
+
+  MyCollidable(Vector2 position)
+      : super(
+          position: position,
+          size: Vector2.all(100),
+          anchor: Anchor.center,
+        ) {
+    addHitbox(HitboxCircle());
+  }
+
+  @override
+  Future<void> onLoad() async {
+    await super.onLoad();
+    final center = gameRef.size / 2;
+    velocity = (center - position)..scaleTo(150);
+  }
+
+  @override
+  void update(double dt) {
+    super.update(dt);
+    if (_isWallHit) {
+      removeFromParent();
+      return;
+    }
+    debugColor = _isCollision ? _collisionColor : _defaultColor;
+    position.add(velocity * dt);
+    _isCollision = false;
+  }
+
+  @override
+  void render(Canvas canvas) {
+    renderHitboxes(canvas);
+  }
+
+  @override
+  void onCollision(Set<Vector2> intersectionPoints, Collidable other) {
+    if (other is ScreenCollidable) {
+      _isWallHit = true;
+      return;
+    }
+    _isCollision = true;
+  }
+}