TO DO
Steps to implement with/for Spreadsheet::Read
Do not strip whitespace of cell contents,
It currently gets me ', but xlsx returns an empty field. It is up to you to decide what you want
And a field with just a single ' should return an empty field, but I would accept a single quote too
a field can hold a single space as valid content. I don't think you should strip trailing spaces by default
Support for cell attributes: background color, text color,
the rest