Header links, Appendable and immutable options 

Sorry, a grab-bag of changes, not really related.

Not 100% sure about the header-link change. It's definitely something that is used (ie see jQuery README file). However, there were no tests for those lines of code that I removed so I don't know what I may have broken.

I've used Appendable, well, just because. Now consumers can pass Writers for streaming.

Finally, creating a custom ProcessingOptions was a pain, so I tweaked it slightly, I hope you don't mind.

As some background. Currently I'm using Pegdown for a project at work, but this seems more suitable for our purposes - it's faster and allows streaming which is always a good sign.