Although Excel has a Date type, older Excel versions use numeric values to store dates.
The value represents the number of days since Jan 1st, 1900.
The only way to tell if the value is a number or a date is to look at the styles.xml and check if the cell has date formatting.
Spout can now read ODS files.
It's on par with the XLSX reader. The only difference is that the row iterator cannot be rewound.
It supports the different output formats from LibreOffice and Excel, skipping extra rows/cells if needed.
Added ODS writer
Refactored XLSX writer to abstract some pieces into an abstract multi-sheets writer
Created an abstract style helper
Moved shared components around
