title: Extjs grid cant get store buffered working
body: <p>I have a large dataset (over 80k records). So I am trying to implement buffer but I couldn't get it work.  If I include buffered configuration I am getting error object doesn't support this property. When I remove it, works ok but of course it takes forever to load the data.</p>
  
  <p>Here is my code</p>
  
  <pre><code>Ext.Loader.setConfig({
      enabled: true,
      disableCaching: false
  });
  
  Ext.require(['Ext.data.*', 'Ext.grid.*',
      'Ext.grid.plugin.BufferedRenderer', 'Ext.ux.grid.FiltersFeature']);
  
  Ext.define('Borrower', {
      extend: 'Ext.data.Model',
      fields: [{
          name: 'Name',
          type: 'string'
      }, {
          name: 'Num',
          type:
              'string'
      }]
  });
  
  Ext.onReady(function () {
  
      var store = Ext.create('Ext.data.Store', {
          autoLoad: false,
          model: 'Borrower',
          pageSize: 100,
          buffered: true, // getting error object doestn support this property in extjs-all-debug.js
          proxy: {
              type: 'rest',
              url: 'borrBuff.xsp/byName',
              reader: {
                  type: 'json',
                  root: 'items'
              }
          }
  
      });
  
      var filters = {
          ftype: 'filters',
          encode: false,
          local: true
      };
  
      var grid = Ext.create('Ext.grid.Panel', {
          id: 'testgrid',
          store: store,
          features: [filters],
          plugins: 'bufferedrenderer',
          columns: [{
              text: 'Borr Name',
              dataIndex: 'Name',
              filterable: true
          }, {
              text: 'Number',
              dataIndex: 'Num'
          }]
      });
  
  })
  </code></pre>
  
  <p>Opening the grid in a window on button click</p>
  
  <pre><code>var grid = Ext.getCmp('testgrid');
  var win = Ext.create('Ext.Window', {
      title: 'Grid Filters Example',
      height: 400,
      width: 700,
      modal: true,
      layout: 'fit',
      items: grid
  }).show();
  grid.getStore().load();
  </code></pre>
  
  <p>Just couldnt figure out what I am doing wrong. Appreciate any help in fixing this issue.</p>