RF: Reimplement prediction for the Fit model of csdeconv.

In the process, I also reorganized the csdeconv module, to put function
definitions at the top, and moved a couple of functions into the shm
module. This should not have too much of an ill effect, I'd think.
RF : move the response estimation back to csdeconv.

Also : seems like the normalization of the prediction matrix by the response
function S0 is a way to normalize the prediction so that this now works rather
nicely. Backed off of making this work for ODF models with no `R`.