Feature Request: Preserve paragraphs

[F1LT3R]

It would be really ud]seful to be able to preserve a paragraph.

For example:

This is the first paragraph. It has two sentences.

This is the second paragraph, it is separated from the first by two (or more) newline characters.

Would it be possible to give the user control of that as an API parameter?

(I've looked into your regex to see if submitting a PR was doable, but it looks figuring it out would probably fry my grey matter in a matter of seconds. If it was an easy change, I'd be open to knowing how much change to the code something like that would require, and where I might try to begin.)