NP scans

Hi Noel,

Can you push this ?
It's not the final version, I still need to implement the merging of the pickles (see multinp).
So far I create a pickle by NP with a list of tuples (NP_val,NLL_val). 
I think it's pretty well advanced so you can have a look and let me know if you want me to modify some parts.

Quentin