really this should be built into natbib, but that hasn't been touched since 2010, so I'm not holding my breath, and I don't want us to be shipping our own incompatible version of natbib, so this seemed like the most sensible place to put it.
I didn't add the xstring extension to handle ending "s"es because I didn't want to introduce another dependency. But if that's ok, then I'll add that as well.
Add the ability to cite papers in a possessive form (which is otherwise impossible to do with natbib).
Fix drawn from: http://tex.stackexchange.com/questions/125690/bibtex-and-genitive-possessive-s-the-proper-way-to-obtain-kurans-1989-mo
really this should be built into natbib, but that hasn't been touched since 2010, so I'm not holding my breath, and I don't want us to be shipping our own incompatible version of natbib, so this seemed like the most sensible place to put it.