Subclassing DWIMs

• Attribute declaration order is stored
• Useful for HTML forms; no need to re-declare the ordering
• This also works with subclassing:

package Super;
use Ernst;
has 'foo', 'bar';

package Sub;
use Ernst;
has 'foo', 'baz';

Sub->meta->metadescription->get_attribute_list; # (foo, bar, baz)