v6.16.2

Fixed

• The hidden attribute of a column and a row was treated as a flag, not as a value of xs:boolean type. Excel writes it as 0/1, but LibreOffice writes false/true, and the string 'false' is truthy in PHP, so the check !empty($attributes['hidden']) turned a visible column into a hidden one. A template made or edited in LibreOffice was saved with all its columns hidden, see #140
• A column whose hidden resolves to false gets the default width again – the attribute is removed now instead of being written as hidden="0", which used to suppress the width
• Sheet::setColVisible($col, true) raised an Undefined array key warning on PHP 8 when the column had no attributes yet