TSV to CSV

Convert tab separated text to CSV, or CSV back to TSV, quoting every field that needs it. A field holding the output delimiter, a double quote, a line break or outer whitespace is wrapped in quotes with inner quotes doubled, which is what stops a value such as Hex bolt, stainless from silently gaining a column. Semicolon output and a UTF-8 byte order mark are there for Excel in comma-decimal locales.