* Render level derived mesh (needed for proper hair rendering) was only calculated before duplication code if the particle object was a level 0 duplicator, so particles creating objects inside a dupligroup didn't work.
* I really don't see the need for the level == 0 check, so I just removed it and after some quick tests can't see any negative effects. If the check is needed for some case though then a more complicated test is needed to handle all cases.