Markdown.pl: don't cuddle up nested lists too closely

When list items are using paragraphs, make sure they do not cuddle
up too closely to the surrounding closing "</li>" when they contain
nested lists.  Also include a "hint" for text-only browsers that
super compact cuddling is not wanted at that spot.

Signed-off-by: Kyle J. McKay <mackyle@gmail.com>

Markdown.pl

@@ -1859,6 +1859,7 @@ sub _ProcessListItems {
 
 	if ($leading_line or ($item =~ m/\n{2,}/)) {
 	    $item = _RunBlockGamut(_Outdent($item));
+	    $item =~ s{(</[OUou][Ll]>)\s*\z}{$1} and $item .= "\n$idt<span style=\"display:none\">&#160;</span>";
 	}
 	else {
 	    # Recursion for sub-lists: