- necessary otherwise the class gf and the namespace have
the same name, leading to some confusion, and need to qualify
some functions (specially on gcc).
Same naming conventions as arrays.
- The old code, which was in the solvers,
is used in several apps (dft, ctqmc_hyb).
It is really a lib, even though it is now superseded
by Igor and Andrey's library...
(to be deprecated at some point).
