Don't convert empty lines between lines into padding.

[RokeJulianLockhart]

As an example, say I have:

This is standard text.

Likewise.

> This is quoted.
> 
> As is this.
> 
> > This is double-quoted.
> > 
> > This is double-quoted.

This is standard text.

Likewise.

If I select solely:

> This is quoted.
> 
> As is this.
> 
> > This is double-quoted.
> > 
> > This is double-quoted.

and use Markdown Here on it, instead of preserving those line breaks without padding, it removed the line breaks, and padded the text. That's not how the rest of my messages are formatted, nor is it an improvement for the accessibility of the document - rather, the opposite.

As an example, download and extract https://github.com/user-attachments/files/16364612/https___github.com_adam-p_markdown-here_issues_721.issue-2427865829.2024-07-24T16_49_04%2B01_00.zip to view the .eml file contained.