Changes to the clone method

This also brings one benefit to classes that provide a clone method that overrides Object's clone method: ...
such classes no longer have to declare their clone method with a return type of Object.
Suppose a program contains the code:
```
Shape tShape = new Shape(100, 200);
Shape tShapeSame = tShape;
```
then both Shape variables point to the same object.
Suppose the class Shape provides a clone method that overrides Object's clone method.
Prior to Java 5, this would have to be declared as:
```
public Object clone()
{
   ...
}
```

And the caller would have to cast the result of the call of clone:

Shape tShape = new Shape(100, 200);
Shape tShapeCopy = (Shape)tShape.clone();

The call can then be simplified to:

Shape tShape = new Shape(100, 200);
Shape tShapeCopy = tShape.clone();