update: wrote the get_gf part.
To be done:
- evaluate the order parameter in ED_OBSERVABLES
- code the fit procedure for the Nambu Green's function
- write the driver for the self-consistency for the Bethe lattice.
- DEBUG - DEBUG - DEBUG - DEBUG - DEBUG - DEBUG - DEBUG - DEBUG - DEBUG

in the middle of writing the superconducting extension of the code.
Code entirely written.
First debug successfull and tested against Massimo Capone lanczos code (MClanc).
Results at first DMFT loop for U=0 and U=1 give very same spectrum.
Green's functions are found in very good agreement and even better
fullfillment of the symmetry (i.e. Re_G or Re_Sigma identically zero).

Initial results for fully converged DMFT calculation obtained for U=2.
Order parameter is found to be on top of MClanc code.

To be fixed:
- Code to be cleaned.
- Delta functions routines in ED_BATH to be replaced with a unique subroutine
for real or matsubara frequencies.
- not interacting Grenn's function (impG0 and impF0) of the Anderson problem looks wrong.
Inversion to be check out.

Test against F. Petocchi results for bethe lattice in order.