small update
update of atom utility
update of some tests
Lots of changes.

Radial grid is simplified. Spline is simplified.
Free atom is properly handeled.
cleaning a lot of things
remove unused function from Radial_grid
simplify Spheric_function
new atom files utility
new atom files utility
tests are updated
version update
version update
Radial_solver class is simplified a little bit
more docs
small fixes