Set the id attribute, admin-page-framework-form, to the form tag.
Removed redundant methods.
Refactored the _getInputFieldOutput() method and made it set _field_name_flat element in the field definition array before passing it to the field rendering callback method.
Fixed a bug in the _getFlatInputFieldName() method that the key element was added with the wrong value.
- Done with the initial reconstruction of the submit field type.
- Added an example to modify the attributes of submit fields in the demo plugin.
- Changed a key name of the field definition array.
Added the support of repeatable fields of the submit field type.
Removed a blank line.