Fix merge from 2.0 for the Spreadsheet Copy (I really don't like this approach, it shouldn't be necessary to save to a temporary file and then restore, a deep clone should be the correct approach)

Author: MarkBaker

src/PhpSpreadsheet/Spreadsheet.php

@@ -3,11 +3,14 @@
 namespace PhpOffice\PhpSpreadsheet;
 
 use PhpOffice\PhpSpreadsheet\Calculation\Calculation;
+use PhpOffice\PhpSpreadsheet\Reader\Xlsx as XlsxReader;
 use PhpOffice\PhpSpreadsheet\Shared\Date;
+use PhpOffice\PhpSpreadsheet\Shared\File;
 use PhpOffice\PhpSpreadsheet\Shared\StringHelper;
 use PhpOffice\PhpSpreadsheet\Style\Style;
 use PhpOffice\PhpSpreadsheet\Worksheet\Iterator;
 use PhpOffice\PhpSpreadsheet\Worksheet\Worksheet;
+use PhpOffice\PhpSpreadsheet\Writer\Xlsx as XlsxWriter;
 
 class Spreadsheet
 {