Additional paragraphs within single list item are improperly rendered

# Description

Consider a document with the following contents:

```
1. One

2. Two

- Two and a half

- Two and three fourths

Two and four sixths

Two and five sixths

3. Three
```

In my tests, the document renders correctly in the preview, but not as expected in the editing view.

Screen captures of both appear below.

As seen, in the editing pane, leading space characters are not correctly interpreted for the list context.

---

# Information

## Environment

- Android version: LineageOS 23.2 (based on AOSP 16)
- Device (phone model): Pixel 4
- Markor version: 2.16.1

## Source

F-Droid

## Format / File type

Markdown

Reproduce the issue in Markor's editing view with the Markdown sample from the report, then compare it with the correctly rendered preview. Trace how leading spaces and additional paragraphs are handled for nested list items in the editing pane; done means the editing view matches the preview for this document.

Written by the indexing model from the issue text.