A text file with CR as line delimiters is recognized as a single line

[marcmo]

we currently accept either CRLF or LF.
But a carriage return (CR) alone can be considered a valid line delimiter in certain contexts.

carriage return (CR) was used as the line delimiter in older Macintosh systems before the adoption of Unix-like line feeds (LF).
we should also support it, either with an option or directly if no line feeds are found.