* Refactor readers to get a proper DI
Similar to what was done with writers, readers also needed to be updated to match the new way of doing things.
This commits promotes a better DI (factories, injection through constructors).
* Escapers should not be singletons
Instead, they should be proper object that can be injected where needed.
* Add option to preserve empty rows when reading an XLSX file
* Add option to preserve empty rows when reading a CSV file
* Add option to preserve empty rows when reading an ODS file
When reading spreadsheets, Spout should be able to return formatted dates, as shown when opened with Excel for instance.
It currently only returns DateTime/DateInterval objects, making it impossible to read + write, as the Writer does not accept objects.
Some software generate [Content_Types].xml file with sheets definition in random order.
Instead of having the first sheet (id = 1) defined first, it may be defined in 3rd position.
Therefore, to read the file in the correct order, sheets order need to be fixed.
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.
