auto-BR is very limited.
When there is a blank line, we should not add a <br /> but a </p><p> (new paragraph) instead.
we'll also need to enclose full post in <p> ... </p>
then we need to remove extra p tags around paragraphs that already had block markup (blockquote, ul, li, etc...)
actually, in this case the p should probably be moved INTO the block
we should use b2evo_formatting existing config to get the list a block elements.
(btw, wordpress tried some stuff for that but it doesn"t
work right in all situations)