Any significant code contributions that you submit must be made available under the terms of the project's license. By submitting a pull request, I assume that you agree to license your code in accordance with the project's license terms, without any additional terms or conditions.
If you would like to contribute a new feature, please file an issue to discuss the feature (unless there's already an issue for that feature). I will consider if the feature makes sense for the application, and I may reject the feature. By filing an issue first, you can avoid wasting time on a feature that I end up rejecting.
If you would like to submit changes that fix a bug or implement an accepted feature, please submit a pull request.