Upgrade nokogiri-diff, allowing us to remove our monkey-patch fixes from the block tests.
Improve Maruku's own HTML parser to handle comments and CDATA better. This improves our ability to identify HTML inside markdown and extract it.
Fix test for issue #40 with improved CDATA handling.
Extract a MaRuKu::HTMLFragment object that abstracts the XML/HTML parser implementation used to handle HTML inside Markdown.
Use REXML to load the entities table (once, at startup) rather than Nokogiri.
Use HTMLFragment in to_html.