Contributions welcome.
Implementation notes are at IMPLEMENTATION.md. If you're unsure about anything, feel free to ask.
Just submit a PR for small changes (bugfixes, typos, etc...). Comment first on existing issues if you're going to work on something to avoid duplication of effort.
Submit an issue for new features before submitting a PR.
Compatibility reports are always helpful. Use the "Compatibility Report" issue template. Ensure you have a working environment and that the site is in the whitelist (check options page).