The old one had various issue, for instance it failed to parse "#hello", and could mis-interpret lines starting with "=". The new one is more robust and handles optional spaces better.

it's useful for the (future) tests being able to compare lines.

we need to terminate the line on the given stream, not on *standard-output*!

Add blockquote support.

was added only to ease the job of the UI, but it isn’t the right place. The UI should do that type of checks, the parsers shouldn’t mangle URIs.