Added HHThreadView

I'm making an iOS library for threaded comment systems. 
![img_8176](https://f.cloud.github.com/assets/853032/2121015/7e88f800-91cf-11e3-8476-cc752895b63b.png)

The quotes beforehand are the result of the news board I'm using that uses NNTP. The text in the cells is purely up to the developer.