title: Insert new elements at specific index - isotope Jquery
body: <p>Is there any way I can insert new elements at a specific index, without using sorting? For example, suppose we have a function like this - <code>isotope('insertAtIndex', elem, 4)</code>, isotope would insert new element 'elem' at 5th position in layout.</p>
  <p>I tried creating my custom function based on 'prepended' function but it just breaks the layout.</p>
  <pre><code>Isotope.prototype.insertAtIndex = function( elems, index ) {
      var items = this._itemize( elems );
      if ( !items.length ) {
          return;
      }
      // add items to beginning of collection
      var previousItems1 = this.items.slice(0, index);
      var previousItems2 = this.items.slice(index);
      this.items = previousItems1.concat(items).concat(previousItems2);
      // start new layout
      this._resetLayout();
      this._manageStamps();
      // layout new stuff without transition
      var filteredItems = this._filterRevealAdded( items );
      // layout previous items
      this.layoutItems( previousItems1 );
      this.layoutItems( previousItems2 );
      // add to filteredItems
      this.filteredItems = filteredItems.concat( this.filteredItems );
  };
  </code></pre>