[theora] NHW Project - improved quality for -l3,-l4,-l5 settings

[Raphael Canut]

Hello,

I have fixed some quantization rounding errors in the encoder and decoder
and so now -l3,-l4,-l5 quality settings are better.This new version is now
really competitive.

I think I have now finished to improve the current quality settings, you
can download this good version at: http://nhwcodec.blogspot.com/ , if you
want to see the many improvements.

Now I will focus on creating -l6 and below high compression settings.

Many thanks!
Cheers,
Raphael