Binaries

[ThomasBaycroft]

Thank you for sending a pull request! :tada:

Proposed changes

Added a binaries branch to include some important effects which are less relevant to single stars, including apsidal precession and some relativistic corrections

Types of changes

What types of changes does your code introduce in kima?

• [X] Bugfix (non-breaking change which fixes an issue) (may need looking at again as the fix needs reversing in some cases)
• [X] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to change)

Tests

I have tested it locally, I am thinking to add an example test for it, maybe Kepler-16?

[j-faria]

Thank you, @TomAB99! This is already very advanced and is working well for you, so I will merge it into the beta branch now and then work on merging that into master together with some new changes I've introduced.