Trying to fix VG paragraphs with preprocess_regexps (didn't work).

Paragraphs in the article body of VG articles aren't <p> tags.  The
text is directly in a <div id="articleBodyText> tag, separated by dual
line breaks ("<br/><br/>").

The first regexp matching the "<div>" seems to work, but the second
regular expression, replacing "<br/><br/>" doesn't do anything that I
can see.  I have tried running just the "<br/><br/>" replacement,
without the "<div>" replacement, but nothing seemed to happen there
either.
Fix VG article paragraphs.

Redefine the preprocess_raw_html method, and do the substitution in
there instead of using preprocess_regexps.

What the current version does is to replace "<br/><br/>" sequences
with "</p><p>" and then it's left to tagsoup to add the missing
paragraph start and end tags.  Seems to be enough.  But more
substitutions may be added for completeness if needed.