Allow formatted strings as argument in PHPToExcel date conversion

Author: MarkBaker

Classes/PHPExcel/Shared/Date.php

@@ -187,7 +187,8 @@ public static function PHPToExcel($dateValue = 0, $adjustToTimezone = false, $ti
             $retValue = self::FormattedPHPToExcel($dateValue->format('Y'), $dateValue->format('m'), $dateValue->format('d'), $dateValue->format('H'), $dateValue->format('i'), $dateValue->format('s'));
         } elseif (is_numeric($dateValue)) {
             $retValue = self::FormattedPHPToExcel(date('Y', $dateValue), date('m', $dateValue), date('d', $dateValue), date('H', $dateValue), date('i', $dateValue), date('s', $dateValue));
-        }
+        } elseif (is_string($dateValue)) {
+            $retValue = self::stringToExcel($dateValue)
         date_default_timezone_set($saveTimeZone);
 
         return $retValue;