[Theora-dev] derf README

[Timothy B. Terriberry]

A number of bug fixes have gone in recently, which improve things 
greatly. I haven't updated the README because I haven't done sufficient 
testing to ensure that everything is truly fixed. The psy model probably 
still needs some work. It can be disabled, but currently only by editing 
some code. In any case, it's still probably not in a position where 
running a bunch of tests and posting pretty graphs on a web page 
somewhere or something similar is worth the time.

The decoder, however, has basically stabilized. If that does not produce 
bit-identical output compared to the mainline decoder, I want to know 
about it. It should also give decent speed improvements over the 
mainline decoder, especially at higher resolutions. I haven't spent (and 
probably won't spend) a lot of time optimizing it or adding SIMD 
assembly support.