title: Backbone collection sortBy
body: <p>I make my first backbone app and get some problems with collection sorting. 
  After using this</p>
  
  <pre><code>var SortedFriends = MyFriends.sortBy(function(friend) {
            return friend.get("uid");
          });  
  </code></pre>
  
  <p>console.log(SortedFriends) show that SortedFriends contains sorted models, but when i try to use collection functions like 'SortedFriends.each' or 'SortedFriends.at' it make error:</p>
  
  <p>TypeError: SortedFriends.each is not a function. </p>
  
  <p>Code:</p>
  
  <pre><code>  var Friend = Backbone.Model.extend({});          
        var Friends = Backbone.Collection.extend({
          model: Friend,            
        });  
  
        var MyFriends = new Friends();
        MyFriends.reset(&lt;?=$friends?&gt;);
  
        var FriendView = Backbone.View.extend({
            initialize: function(){
                model:Friend            
            },              
            tagName: "tr",
            template: _.template($('#item-template').html()),
            className: "document-row",          
            render: function() {                              
  
           this.$el.html(this.template(this.model.toJSON()));                            
                return this;             
            }          
        });     
  
  
      var SortedFriends = MyFriends.sortBy(function(friend) {
        return friend.get("uid");
      });          
  
      var addOne = function(element){           
          var view = new FriendView({model: element});
          $("#friends").append(view.render().el);
      }                              
      console.log(JSON.stringify(SortedFriends));
      SortedFriends.each(function(friend){
          var view = new FriendView({model: friend});
          $("#friends").append(view.render().el);            
      });
  </code></pre>