todo: move to reproduce directory

Joonki Noh's code for DE CT restoration,
modified by JF.

@a noh:09:ssr ieee-t-mi 28 11 1688-702 nov 2009
Joonki Noh  J A Fessler  Paul E Kinahan
Statistical sinogram restoration in dual-energy CT for PET attenuation correction
@u doi 10.1109/TMI.2009.2018283

In the "old" directory has older versions of his tools.
Could be deleted eventually, after I am sure that the main code runs fine.