Line breaks aren't properly ignored in lists

[michaelee]

While line breaks are properly ignored in body text (by the TUI), they aren't ignored when they appear in lists of any sort.

E,g., consider the following markdown:

1. This shouldn't have
   a line break
2. This should have\
   a line break

- This shouldn't have
  a line break
- This should have\
  a line break

Definition list
: This shouldn't have
  a line break
: This should have\
  a line break

In all the lists, both list items contain explicit line breaks. If line breaks are ignored (i.e., not preserved), then the first list item of each list should be rendered on a single line (then reflowed as necessary).

Per pandoc:

cat test.md | pandoc -f markdown -t plain
1.  This shouldn’t have a line break
2.  This should have
    a line break

- This shouldn’t have a line break
- This should have
  a line break

Definition list
    This shouldn’t have a line break
    This should have
    a line break