Fix bug that will ignore new lines

Hi Chris

This is quite a bug: We forgot to put the re.DOTALL flag in the regex. So newlines are ignored when interpreting .

That means our new functionality will work for this: <pre>Hello World</pre>
But it will not work for this:
<pre>
Hello
World
</pre>

I have updated the regex and things seem to work fine. Please can you confirm and publish if happy.