exercice 1 and a bit of the 2

src/main/java/shape/AbstractShape.java

src/main/java/shape/App.java

src/main/java/shape/BorderDecorator.java

src/main/java/shape/CenterDecorator.java

src/main/java/shape/Circle.java

src/main/java/shape/Decorator.java

src/main/java/shape/Drawer.java

src/main/java/shape/Polygon.java

src/main/java/shape/Rectangle.java

src/main/java/shape/Shape.java

src/main/java/shape/ShapeContainer.java