Definition of angle for F82

[natyh]

The specification says (in the comments on equation (43), that the angle for F82 is defined as 82 degrees. This is not accurate - the actual angle should be defined as arccos(1/7), which is close to but not exactly 82 degrees. In other words, mu_bar is defined as exactly 1/7. This is needed for the math to work out with integer powers, etc.

[portsmouth]

Thanks Naty, I will make a PR to fix up that mistake.

[portsmouth]

See #90

[jstone-lucasfilm]

Thanks for the fix, @portsmouth!