Style guide and coding conventions

• Identifier names should not contain abbreviations unless those abbreviations are very widely used and understood (e.g. "KL divergence").
• Comments should start with a capital letter and end with a period. They should use correct grammar and spelling.
• Function and method signatures must be fully type-annotated, including the return type (if any).
• Every Python code file must start with an SPDX/Copyright header.
• Settings descriptions should start with a capital letter and end with a period.
• When new settings are added in config.py, they should also be added to config.default.toml, set to their default value and with their description as a comment. The order of settings in config.default.toml should match that in config.py.
• Pull requests should implement one change, and one change only.
  • PRs containing multiple semantically independent changes must be split into multiple PRs.
  • PRs must not change existing code unless the changes are directly related to the PR. This includes changes to formatting and comments.