feature: replace Relative GF by saturation, computational only Replace Relative GF by saturation. The saturation code is derived from the hwOS repo. This commit only contains the Buhlmann computational part. In the simulator, the numbers does look sane. The initial ascent from the bottom phase stops at the deepest deco stop a little over GFlow, which is correct in my view, as we still have some time to spend on this deepest stop, and that stop ends very close to GFlow (obviously, a deepest stop is typically short, as in 1 or 2 minutes). The deco finally ends at the surface with a saturation value of GFhigh. Signed-off-by: Jan Mulder <jlmulder@xs4all.nl>