MJPEG Tools Svn

Completed initial experiments with gradient descent.
Solved problem with inaccurate fast integer quantisation
calculations (for now.... maybe) and completed porting over
of available MMX routines. There's really very little left in
the code that can benefit from this. One or two more routines plus
extending the fast MMX stuff to the other quantisation routines.

Basically, if it survives a couple of movie-length tests its
ready for beta.