Incorrect handling of list entry text

To add multiple lines of text to a list entry one should indent the text below the entry to signify that it belongs to it. This sign isn't currently looked for by termimad, so the text of a sub-list entry is highlighted as a codeblock (since it is indented 4 spaces).

Adding some statefulness to the printing, to track if printing indented lines after a list entry of which depth, would be a nice improvement.

Start by tracing how termimad prints Markdown list entries and indented lines, then reproduce the issue with a list entry followed by multiple indented lines. Done means continuation text remains part of the list entry instead of being highlighted as a code block.

Written by the indexing model from the issue text.