Fix and wrap set_tail_from_fit

The c++ version of the tail fit is wrapped to python. I also changed
slightly the code so that when replace_by_fit is true the data is
changed all the way to the end of the Matsubara axis not only on the
interval where the fit was done.
Added predefined hamiltonians to operators
Merge branch '1.2-dev' of github.com:TRIQS/triqs into 1.2-dev
Put hilbert_space_tools in sync with cthyb