Support to migrating data to a group

add-data.php

<?php
$data = array(
	array(
		'year' => 2013,
		'title' => 'Test',
		'wins' => 1,
		'podiums' => 2,
		'poles' => 3,
		'description' => 'test description',
	),
	array(
		'year' => 2014,
		'title' => 'Test Title 2',
		'wins' => 1,
		'podiums' => 2,
		'poles' => 3,
		'description' => 'Test Description 2'
	)
);

$post_id = 1;
$group_id = 'group';

update_post_meta( $post_id, $group_id, $data );

register-meta-boxes.php

<?php
add_filter( 'rwmb_meta_boxes', function( $meta_boxes )
{
	$meta_boxes[] = array(
		'title' => 'Group Test',
		'fields' => array(
			array(
				'id' => 'group', // Must match $group_id
				'name' => 'Group',
				'type' => 'group',
				'clone' => true,
				'fields' => array(
					array(
						'id' => 'year',
						'name' => 'Year',
						'type' => 'text',
					),
					array(
						'id' => 'title',
						'name' => 'Title',
						'type' => 'text',
					),
					array(
						'id' => 'wins',
						'name' => 'Wins',
						'type' => 'text',
					),
					array(
						'id' => 'podiums',
						'name' => 'Podiums',
						'type' => 'text',
					),
					array(
						'id' => 'poles',
						'name' => 'Poles',
						'type' => 'text',
					),
					array(
						'id' => 'description',
						'name' => 'Description',
						'type' => 'textarea',
					),
				),
			),
		),
	);
	return $meta_boxes;
} );