change default writer to PHPExcel_Writer_Excel2007

Author: mikehaertl

README.md

@@ -57,7 +57,7 @@ For now we only provide some usage examples instead of a full documentation.
 $file = \Yii::createObject([
     'class' => 'codemix\excelexport\ExcelFile',
 
-    // Default writer is Excel 5. You can use any other writer available from PHPOffice.
+    // Default writer is `\PHPExcel_Writer_Excel2007`. You can use any other writer available from PHPOffice.
     //'writer' => '\PHPExcel_Writer_Excel5',
 
     'sheets' => [

src/ExcelFile.php

@@ -11,9 +11,9 @@
 class ExcelFile extends Object
 {
     /**
-     * @var string the writer class to use. Default is `\PHPExcel_Writer_Excel5`.
+     * @var string the writer class to use. Default is `\PHPExcel_Writer_Excel2007`.
      */
-    public $writer = '\PHPExcel_Writer_Excel5';
+    public $writer = '\PHPExcel_Writer_Excel2007';
 
     protected $_workbook;
     protected $_sheets;