title: jquery datatables sorting neglect null value
body: <p>I'm using datatables and jQuery for making nice sortable tables. I now want to sort the rows an a value. This value is a numeric value. But it can also be not available, so at that point I will echo a dash.</p>
  
  <p>When I now sort this column, all rows with the dash are on top. And than the rows with value 1, 3, 6, 8, 10 are shown. How do I change this so that the dash (-) are always on bottom of the table?</p>
  
  <p>At the moment I put in a maximum number, what puts them on the bottom. However I don't want this value to be shown to the user. So I need a hidden sort column, or a other sorting method.</p>
  
  <p>Thanks in advance!</p>