[doc] added note on hdf5 for dictionaries
[doc] modifications to installation
[gfs] Add map for block functions
Fix hdf5 formats

- h5 : Python :
- h5 : C++ : add options 'w', 'r', 'a' for C++ file constructor
  to mimic Python
- block gf : clean the hdf5 format and save/load difference between
  Python and C++
- rewrite gf_base_op test to eliminate the h5 file (big).