Added Cajun class for formatting and rendering extensions

[andyleap]

Hey, this is just something that I worked on for the wiki I'm writing(over at https://github.com/GoWiki/GoWiki) I wanted to add the ability to color links, based off of info like if a page exists on the wiki or not, but there wasn't any easy way that I could see. Let me know if you think a different way would be better.

[m4tty]

Ok, I see what you need. I've thought about how to add/modify the html elements a bit... and might do something a bit larger in scope. e.g. allow a change to any element for a given transform.

[andyleap]

Would be a rather big change, but it'd be neat to extract out the "renderer" portion, and be able to make a custom renderer. A neat side effect would, If done correctly, would be the ability to render to things other then html, like pdf and such. Would be neat to be able to have a "download as pdf" button on my wiki.