Create simple ajax tables

• To make column sortable add at-sort class to the <th> element
• To make column hidable add at-hide class to the <th> element
• Set the id property of the <th> element.
  • The value of id will be passed as an argument to the order_by() function of the table's queryset on sorting
  • The id will be a key in the var hidden which is given to the template, so you can check whether the column is hidden or not
• Add at-show-hidden to one <th> where you want the "Show hidden columns" button to be placed