gf. clean data_proxy and h5 writing
gf : clean name

- data_view, singularity_view
- check && and co for noexcept
time_pt : add operator = double

- add assigment to double
(for QMC, needed when taking a random number).
utility/dress_iterator : generalize constructor

- to handle automatic construction of a dressed_iterator of
a const_iterator from the iterator (and not only the const_iterator).

- added move semantics