`cellText` parse option controls `.w` output (fixes #640 h/t @SCullman)
- UTF-16 Unicode Text (TXT) write - Lotus Formatted Text (PRN) read/write - DBF version 2 field length adjustments - throw errors if SheetNames is invalid (fixes #376 h/t @pietersv)
- multiformat column widths (fixes #591 h/t @sheeeeep) - skip nested BIFF files