This updates the cubic root functions to remove the old unused functions and make three options available. 1) if a real root doesn't exist for liquid or vapor, report the root that does exist. 2) if a real root doesn't exist for liquid or vapor, report NAN for the root that doesn't exist. 3) if a real root doesn't exist report a fake root for the root that doesn't exist. A jupyter notebook was added to the cubic root finder code that explains the fake root.
This updates the cubic root functions to remove the old unused functions and make three options available. 1) if a real root doesn't exist for liquid or vapor, report the root that does exist. 2) if a real root doesn't exist for liquid or vapor, report NAN for the root that doesn't exist. 3) if a real root doesn't exist report a fake root for the root that doesn't exist. A jupyter notebook was added to the cubic root finder code that explains the fake root.