title: when I set postData in jqGrid, it is not serialized properly on reload
body: <p>I have jqGrid which is initially empty (I return data from server only when _search is true).
  This is grid code:</p>
  
  <pre><code>jQuery(gridId).jqGrid({
                      url : '/controller/GetData',
                      height : 100,
                      multiplesearch : true,
                      datatype : "json",
                      mtype : "POST",
                      rowNum : 10,
                      rowList : [ 10, 20, 30 ],
                      sortname : 'LBONumber',
                      sortorder : "desc",
                      viewrecords : true,
                      onSelectRow: jqGridRowSelected,
                      caption : 'DATA',
                      colNames : ["LBO","First name","Adress"],
                      colModel : [{"name":"LBONumber","index":"LBONumber","hidden":false},{"name":"FirstName","index":"FirstName","hidden":false},{"name":"Adress","index":"Adress","hidden":false},
      });
  </code></pre>
  
  <p>I have text field with id "LBO" and on click of a button I execute this code:</p>
  
  <pre><code>$(gridId).setGridParam({
                              search: true,
                              postData: {
                                  'filters':$.param({
                                      'groupOp': 'AND',
                                      'rules': [{ "field": 'LBONumber', "op": 'eq', "data": function () { return $("#LBO").val() } }]
                                  })
                              }
                          });
  </code></pre>
  
  <p>My problem is request body, which is:</p>
  
  <pre><code>_search=true&amp;nd=1306834594225&amp;rows=10&amp;page=1&amp;sidx=LBONumber&amp;sord=desc&amp;filters%5BgroupOp%5D=AND&amp;filters%5Brules%5D%5B0%5D%5Bfield%5D=LBONumber&amp;filters%5Brules%5D%5B0%5D%5Bop%5D=eq&amp;filters%5Brules%5D%5B0%5D%5Bdata%5D=333
  </code></pre>
  
  <p>It should say <code>...filters=...</code>, not <code>...filters%5B...</code> and I don't want to process it on server, it must be a proper way of making this work. I know that this is actually properly serialized object, but I need this my function to work same way as jqGrid's included search, as I already have server-side code done for that case.</p>