UPDATE [CODE RESHUFFLED]:
we update the wrap of ED solver by exploding the main ed_solve_impurity routine, which
was performing all the tasks: i. solve ed problem, ii. get local GF, iii. get
updated Weiss field and fit new bath, into three new different class of routines (overloading
the different cases).
We tested the new version of the code with respect to the old one and got numerically identical
results (tested with diff).