Make newer Excel versions properly recalculate formulas on document open

Fixes #456
Closes #515

Author: Toni Martí

src/PhpSpreadsheet/Writer/Xlsx/Workbook.php

@@ -175,6 +175,7 @@ private function writeCalcPr(XMLWriter $objWriter, $recalcRequired = true)
         //    fullCalcOnLoad isn't needed if we've recalculating for the save
         $objWriter->writeAttribute('calcCompleted', ($recalcRequired) ? 1 : 0);
         $objWriter->writeAttribute('fullCalcOnLoad', ($recalcRequired) ? 0 : 1);
+        $objWriter->writeAttribute('forceFullCalc', ($recalcRequired) ? 0 : 1);
 
         $objWriter->endElement();
     }