fix DataGrid::createSorting() $sort_callback was nullable for init request -> problem with sofistic QueryBuilder use-cases
fix DataGrid::createSorting()
$sort_callback was nullable for init request -> problem with sofistic QueryBuilder use-cases

harmim/datagrid,ublaboo/datagrid,chapcz/datagrid,ublaboo/datagrid,chapcz/datagrid,harmim/datagrid