add 'setRefClass' as a keyword
add 'setRefClass' as a keyword

`setRefClass` is used to generate reference classes in R, and given the commonly used `S4` methods status as keywords, it makes sense to add `setRefClass` as well.
jar1karp/rstudio,JanMarvin/rstudio,thklaus/rstudio,jrnold/rstudio,john-r-mcpherson/rstudio,more1/rstudio,more1/rstudio,githubfun/rstudio,john-r-mcpherson/rstudio,piersharding/rstudio,tbarrongh/rstudio,jar1karp/rstudio,JanMarvin/rstudio,nvoron23/rstudio,more1/rstudio,brsimioni/rstudio,githubfun/rstudio,vbelakov/rstudio,githubfun/rstudio,JanMarvin/rstudio,john-r-mcpherson/rstudio,JanMarvin/rstudio,jar1karp/rstudio,githubfun/rstudio,thklaus/rstudio,sfloresm/rstudio,maligulzar/Rstudio-instrumented,pssguy/rstudio,edrogers/rstudio,edrogers/rstudio,jar1karp/rstudio,thklaus/rstudio,JanMarvin/rstudio,pssguy/rstudio,maligulzar/Rstudio-instrumented,sfloresm/rstudio,jzhu8803/rstudio,vbelakov/rstudio,tbarrongh/rstudio,brsimioni/rstudio,JanMarvin/rstudio,pssguy/rstudio,JanMarvin/rstudio,suribes/rstudio,JanMarvin/rstudio,more1/rstudio,vbelakov/rstudio,jrnold/rstudio,brsimioni/rstudio,maligulzar/Rstudio-instrumented,jrnold/rstudio,pssguy/rstudio,pssguy/rstudio,suribes/rstudio,thklaus/rstudio,jar1karp/rstudio,jrnold/rstudio,john-r-mcpherson/rstudio,maligulzar/Rstudio-instrumented,jrnold/rstudio,vbelakov/rstudio,pssguy/rstudio,vbelakov/rstudio,githubfun/rstudio,piersharding/rstudio,jzhu8803/rstudio,suribes/rstudio,tbarrongh/rstudio,pssguy/rstudio,sfloresm/rstudio,githubfun/rstudio,brsimioni/rstudio,edrogers/rstudio,thklaus/rstudio,jar1karp/rstudio,john-r-mcpherson/rstudio,suribes/rstudio,more1/rstudio,piersharding/rstudio,jzhu8803/rstudio,edrogers/rstudio,piersharding/rstudio,suribes/rstudio,thklaus/rstudio,edrogers/rstudio,sfloresm/rstudio,tbarrongh/rstudio,tbarrongh/rstudio,sfloresm/rstudio,maligulzar/Rstudio-instrumented,nvoron23/rstudio,edrogers/rstudio,jar1karp/rstudio,brsimioni/rstudio,tbarrongh/rstudio,nvoron23/rstudio,jrnold/rstudio,brsimioni/rstudio,jar1karp/rstudio,pssguy/rstudio,piersharding/rstudio,suribes/rstudio,maligulzar/Rstudio-instrumented,nvoron23/rstudio,nvoron23/rstudio,jzhu8803/rstudio,vbelakov/rstudio,thklaus/rstudio,piersharding/rstudio,JanMarvin/rstudio,vbelakov/rstudio,sfloresm/rstudio,jrnold/rstudio,edrogers/rstudio,jzhu8803/rstudio,maligulzar/Rstudio-instrumented,tbarrongh/rstudio,jzhu8803/rstudio,jzhu8803/rstudio,piersharding/rstudio,brsimioni/rstudio,maligulzar/Rstudio-instrumented,maligulzar/Rstudio-instrumented,nvoron23/rstudio,john-r-mcpherson/rstudio,vbelakov/rstudio,more1/rstudio,nvoron23/rstudio,piersharding/rstudio,brsimioni/rstudio,jrnold/rstudio,john-r-mcpherson/rstudio,thklaus/rstudio,john-r-mcpherson/rstudio,jrnold/rstudio,edrogers/rstudio,more1/rstudio,piersharding/rstudio,tbarrongh/rstudio,jzhu8803/rstudio,sfloresm/rstudio,sfloresm/rstudio,githubfun/rstudio,suribes/rstudio,more1/rstudio,suribes/rstudio,githubfun/rstudio,jar1karp/rstudio