Use the same logic in ThreadViewer to apply greentext in the board view
I've rewritten the greenext replace regex.  I've tried to account for
the most common cases and it seems to be working better than before.
There will still be times where it fails to color but I don't think there is a
way to handle all cases currently.  I think  ideally we should be
replacing the <a class="quote"> tags with the font color before
sanitizing the input.
remove unused pattern
Merge pull request #420 from yate/greentext-board-view

Use the same logic in ThreadViewer to apply greentext in the board view