Problem to read a xlsx file saved with libreoffice

```
I have a xlsx file, generate with Excel program, and I open it with libreoffice
(under Ubuntu). After I saved it in xlsx format, php-excel-reader make an error
like :
Fatal error: Uncaught exception 'PHPExcel_Calculation_Exception' with message
'Maubert!B2 -> Formula Error: An unexpected error occured' in
/var/www/transect/plugins/phpExcel-1.8.0/Classes/PHPExcel/Cell.php on line 300

If the file is saved as ods file, it can be loaded (but others errors occur).

Tanks,

Eric.
```

Original issue reported on code.google.com by `quinton....@gmail.com` on 17 Jun 2014 at 7:27

Start with the reported XLSX workflow: open the Excel-generated file in LibreOffice on Ubuntu, save it as XLSX, and load it with php-excel-reader. Inspect PHPExcel/Cell.php around line 300 and the reported Maubert!B2 formula error. Done means reproducing the failure and identifying a verified fix or a precise explanation of the unsupported formula or file condition.

Written by the indexing model from the issue text.