[Possible Bug]: Additional <p> wrapper around HTML input

[Milian Wolff]

I hope this is not by design and not an already discussed bug.

Take the following input:

    <hr id="foo" />
    
    <hr id="foo">

    <hr id="foo"/>

    <hr id="foo" />
    <hr id="foo">
    <hr id="foo"/>

If this is run through Markdown a paragraph will wrap hr's numer 4-6. This 
behaviour can be found in both Markdown.pl and Markdown.php (I used the 
Dingus provided on the project pages).

Interesting is, that Markdown Extra handles this correctly.

PS: The above input is a snippet from `MDTest/markdown.mdtest/Inline HTML 
(Simple).text`
-- 
Milian Wolff
http://milianw.de