Hard line breaks are not respected

[makew0rld]

Reported by tiwesdaeg on IRC.

According to the markdown spec, lines with two spaces at the end should stay on their own line. They shouldn't be joined with a paragraph above, and shouldn't have blank lines inserted above them.

There are other ways to cause these "hard line breaks", and md2gemini should support all of them to stay in the Markdown spec. See https://spec.commonmark.org/0.29/#hard-line-breaks .

[makew0rld]

The mistune v2 HTML renderer seems to respect this, meaning it needs to be fixed on my end.

Python 3.8.3 (default, May 17 2020, 18:15:42) 
[GCC 10.1.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import mistune
>>> mistune.__version__
'2.0.0a4'
>>> text = """
... line with two spaces  
... another line, regular
... regular line
... line with two spaces again  
... """
>>> mistune.html(text)
'<p>line with two spaces<br />\nanother line, regular\nregular line\nline with two spaces again</p>\n'