BXMLSerializer should call bind() on superclasses when appropriate

Scenario:

public class A {
}

public class B extends A implements Bindable {
@BXML Foo foo;

@Override
public void initialize(...)

{ System.out.println(foo.getClass().getSimpleName()); }

}

public class C extends B {
@BXML Bar bar;

@Override
public void initialize(...)

{ super.initialize(); System.out.println(bar.getClass().getSimpleName()); }

}

Now, in test.bxml, you have:

<C/>

You expect the following output:

"Foo
Bar"

And yet we only bind the object to class C, meaning you instead will get a NullPointerException trying to de-reference 'foo'.

We should bind to all classes that implement Bindable.