Fix hdf5 formats

- block gf : clean the hdf5 format
- doc
Add Fourier for lattice. Clean

- clean a bit (factorize the call for matrix case, assignment delegation).
- Add regular_bz_mesh, cyclic_lattice, and their FFT.
[gfs] Remove freq_infty

- rm freq_infty.
- The gf can now be evaluated on a tail_view, which result in
  composing the tail.
- Fix the following issue :
  g(om_) << g(om_ +1)
  will recompose the tail correctly.
- TODO : TEST THIS NEW FEATURE IN DETAIL.
[gfs] Work on singularity for G(x, omega)

- G(k,omega), G(r, omega) : singularity in m_tail.hpp
- Separate the factory for singularity from the data factory in gf.
- overload assign_from_functoin (renamed).
- Fix singularity_t and co in the gf (const issue).
- Appears not to be the best implementation option ....
  To be discussed.