Allow multiple blank lines

[WalterPongratz]

This thing is great.

One addtional idea to allow line breaks to look like in editor: When there are multiple consecutive line breaks, add   - that way multiple consecutive line breaks get preserved

[bkis]

Thank you for the idea, sounds good! I am pretty busy recently, but I'll look into this at some point. Or – if you're interested in contributing – PRs are very welcome, too.