This is a definite possibility for NG. The thing is that one of the basic premises of the project was to have as little external dependencies as possible - but it might be time to move away from that.

Also, about the plugin engine - I think we should definitely go to NG with it, what do you SAY @colesmj ? My worry is to end up with two ways of having rules and making it more difficult for people to add rules, without clear reasoning. I'd prefer a clean break and move to the new ways, leaving people on 1.x if they prefer that functionality rather than potentially breaking running stuff.