Metapost: Style Updates

Not much to report, just spent a while making minor changes to the look of blog posts -

• Code snippets now use the excellent SyntaxHighlighter by Alex Gorbatchev (chances are you've seen this already, it's pretty popular, and with good reason!).
• I've updated the CSS so error, warning, tip and note boxes are all styled. I also went back and updated the posts that were put up before I thought of these. If you want to see what these look like, take a look at the TortoiseSVN with SVN+SSH post or the Hacking the Cisco 7940 IP Phone post.
• Some minor updates to content and to styles so that everything is more consistent