blockquote inside list do not work

[DenisDuev]

Same as: #242, the difference is that the blockquote is inside list.

For example:

1. list
  > blockquote

Returns:

<ol>
<li>list
&gt; blockquote</li>
</ol>

Expected:

<ol>
<li>list</li>
</ol>
<blockquote>
<p>blockquote</p>
</blockquote>

[miekg]

a list in go-markdown needs a newline to tell the parser it has block level elements. Your list example doesn't have a newline, so the parser doesn't do that scan. Can we always set `ast.ListItemContainsBlock`? Dunno