code: function _fnNodeToColumnIndex( oSettings, iRow, n )
  	{
  		return $.inArray( n, oSettings.aoData[ iRow ].anCells );
  	}
docs: Take a TD element and convert it into a column data index (not the visible index)
  @param {object} oSettings dataTables settings object
  @param {int} iRow The row number the TD/TH can be found in
  @param {node} n The TD/TH element to find
  @returns {int} index if the node is found, -1 if not
  @memberof DataTable#oApi