v2023.12.1

Improvements to the documentation and documentation build process.

• Docstrings in the Python project files have been formatted for better rendering and numerous small inconsistencies and errors have been corrected.
• Restructured the project so that the Fortran code does not have to be compiled when generating documentation for swiftest.readthedocs.io.
• Refactored many swiftest.io functions to indicate that they are not part of the public API.
• Added a more comprehensive list of sections to the API page.