ext columnmodel获取任意列的值

renderer有6个参数：

引用* value : Object
The data value for the cell.

* metadata : Object
An object in which you may set the following attributes:
? o css : String
??? A CSS class name to add to the cell's TD element.
? o attr : String
??? An HTML attribute definition string to apply to the data container element within the table cell (e.g. 'style="color:red;"').

* record : Ext.data.record
The Ext.data.Record from which the data was extracted.

* rowIndex : Number
Row index

* colIndex : Number
Column index

* store : Ext.data.Store
The Ext.data.Store object from which the Record was extracted.

第3个参数就是record，用record.get(fieldName)来取其它列的值。例：record.get("card_admin")