Use DIV not BR for paragraph separation

Perhaps would be better to render vertical space between paragraphs (represented as an empty line in source wike text) as <dev style="height:1em"/> rather then as <br/>.

<br/> seems to be rendered unreliably, see for instance

Before.B

• item.B1
• item.B2

after.B

which is rendered as

Before.B<br/>

<ul class="star">
<li> item.B1</li>

<li> item.B2</li>
</ul><br/>
After.B

which in tern is rendered without any vertical space between "Before.B" and "item.B1" in all of the browsers mentioned in "Environment" section of this bug report.

(Note: I have erroneously entered this as a second test case into CONF-1601 which I regret bitterly – it's a separate bug)