Contributing to tween.js

1. Always make your contributions for the latest dev branch, not master. So before doing anything else, switch to the dev branch.
2. And starting from there, create a new branch for each patch or feature you want to contribute.
3. Once done with a patch / feature, do not add more commits to a feature branch (pull requests are not repository state snapshots; any change you do in that branch will be included in the pull request).
4. If you add a new feature, please also add an example and/or tests (both for showing how it's used and for testing it still works after eventual refactorings).
5. If you add some assets for the examples (images, sounds, etc), make sure they have a proper license allowing for their use here (the less restrictive, the better).
6. If you modify existing code (refactoring / optimization / bug fix), run the unit tests to ensure nothing broke, and run relevant examples to check they didn't break or that there wasn't any performance regression. The tests are in the test/unit folder; examples are in the examples folder.
7. If any GitHub issue is relevant to the patch / feature, it's good to mention the issue number with a hash (e.g. #2774) in a commit message, to get it cross-referenced in GitHub's web interface.
8. Format whitespace consistently with the rest of code base.

Guidelines heavily inspired by three.js's Contributing page--THANK YOU!