TO DO

Steps to implement with/for Spreadsheet::Read

1. 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

2. Support for cell attributes: background color, text color,

3. the rest