oceani: redo parsing of blank lines.

oceani: redo parsing of blank lines.

I've been puzzling how best to write a grammar to
handle blank lines and option line-breaks well.
The "OptNL" approach didn't work, and "Newlines"
only sometimes works.

I won't try to explain all the logic here, but I do plan to write a
blog post about it soon.

Signed-off-by: NeilBrown <neil@brown.name>