Revamp LINES

[paulapatience]

• Keep empty lines.
• Handle more EOL characters (CRLF in particular is tricky).
• Optionally keep EOL characters in the lines.

Although keeping empty lines is a backwards-incompatible change, I would argue that omitting empty lines from the result is a bug. For instance, it prevents you from being able to count the lines in a file.

I failed in getting docs.lisp to update REFERENCE.md.

[paulapatience]

I made the changes you requested and additionally embellished the examples.