Migrate examples back, change to monorepo (#701)

examples/lib/commons/square_component.dart

@@ -0,0 +1,18 @@
+import 'dart:ui';
+
+import 'package:flame/components.dart';
+import 'package:flame/palette.dart';
+
+class SquareComponent extends PositionComponent {
+  Paint paint = BasicPalette.white.paint;
+
+  SquareComponent() {
+    size = Vector2.all(100.0);
+  }
+
+  @override
+  void render(Canvas c) {
+    super.render(c);
+    c.drawRect(size.toRect(), paint);
+  }
+}