New issues with bug reports or new feature proposals are welcome of course - but nothing speaks like proposed code and pull requests.. thus that's the preferred way of contributing to this project! To propose a change, do the usual GitHub thing (or glance at guides.github.com if this is your first contribution to an open source project on GitHub - welcome!):
Pull this, create a local branch.
Then, hack some cool extension, bug fix, etc.
Raise Pull Request...
Thanks for your help!