title: jqgrid column model extend and add more properties
body: <p>I have a jqgrid code as follows. I wanted to add a custom property to the colmodel same as <strong>myproperty</strong> in the code below. </p>
  
  <pre><code>...
  jQuery("#list2").jqGrid({
      url:'myurl',
      datatype: "json",
      colNames:['Inv No','Date', 'Client', 'Amount','Tax','Total','Notes'],
      colModel:[
          {name:'id',index:'id', width:55},
          {name:'invdate',index:'invdate', width:90, myproperty:{prop1:'true', prop2:1}},
          {name:'name',index:'name asc, invdate', width:100, myproperty:{prop1:'false', prop2:2}},
          {name:'amount',index:'amount', width:80, align:"right"},
          {name:'tax',index:'tax', width:80, align:"right"},      
          {name:'total',index:'total', width:80,align:"right"},       
          {name:'note',index:'note', width:150, sortable:false}       
      ],
      rowNum:10,
      rowList:[10,20,30],
      pager: '#pager2',
      sortname: 'id',
      viewrecords: true,
      sortorder: "desc",
      caption:"JSON Example"
  });
  jQuery("#list2").jqGrid('navGrid','#pager2',{edit:false,add:false,del:false});
  </code></pre>
  
  <p>The need for this is because I want to pass some properties to each column and get it later as follows. Lets say I want myproperty for row 1. I would do that</p>
  
  <pre><code>var rowId=1
  var colmodel= jQuery("#list2").jqGrid('getGridParam', 'colModel');
  var myProperty = colmodel[rowid].myproperty; 
  </code></pre>