N°6414 Separate SubFormField and Scalar fields

This will help to set methods as final, as SubFormField is often the sole one to have a real custom impl

sources/Form/Field/SelectObjectField.php

@@ -39,7 +39,7 @@ use utils;
  * @author Romain Quetiez <romain.quetiez@combodo.com>
  * @since 2.3.0
  */
-class SelectObjectField extends Field
+class SelectObjectField extends AbstractSimpleField
 {
 	/** @var int CONTROL_SELECT */
 	const CONTROL_SELECT = 1;