title: Simple Slickgrid sorting doesn't work
body: <p>Is there obvious reason why this Slickgrid example shouldn't work. Basically it doesn't sort on clicking columns.</p>
  
  <pre><code>        var grid;
  
          var columns = [
          {id:"title", name:"Title", field:"title", sortable: true},
          {id:"duration", name:"Duration", field:"duration", sortable: true},
          {id:"%", name:"% Complete", field:"percentComplete", sortable: true},
          {id:"start", name:"Start", field:"start", sortable: true},
          {id:"finish", name:"Finish", field:"finish", sortable: true},
          {id:"effort-driven", name:"Effort Driven", field:"effortDriven", sortable: true}
          ];
  
          var options = {
              enableCellNavigation: true,
              enableColumnReorder: false
          };
  
          $(function() {
              var data = [];
              for (var i = 0; i &lt; 500; i++) {
                  data[i] = {
                      id: i,
                      title: "Task " + i,
                      duration: "5 days",
                      percentComplete: Math.round(Math.random() * 100),
                      start: "01/01/2009",
                      finish: "01/05/2009",
                      effortDriven: (i % 5 == 0)
                  };
              }
  
              var dataView = new Slick.Data.DataView();
  
              grid = new Slick.Grid("#myGrid", dataView, columns, options);
              function comparer(a,b) {
                  var x = a[sortcol], y = b[sortcol];
                  return (x == y ? 0 : (x &gt; y ? 1 : -1));
              }
  
              var sortcol = "json_number";
              var sortdir = 1;
              grid.onSort.subscribe(function(e, args) {
                  sortdir = args.sortAsc ? 1 : -1;
                  sortcol = args.sortCol.field;
  
                  // using native sort with comparer
                  // preferred method but can be very slow in IE with huge datasets
                  dataView.sort(comparer, args.sortAsc);
              });
              dataView.beginUpdate();
              dataView.setItems(data);
              dataView.endUpdate();
              grid.invalidate();
              grid.render();
  
              $("#myGrid").show();
          })
  </code></pre>