Revert "no native support for MML in markdown mode"
Revert "no native support for MML in markdown mode"

This reverts commit 10004c83c31e5aa2a23cc5bb7be6ab77db28a1f0.

sfloresm/rstudio,edrogers/rstudio,suribes/rstudio,jrnold/rstudio,thklaus/rstudio,piersharding/rstudio,githubfun/rstudio,jzhu8803/rstudio,githubfun/rstudio,githubfun/rstudio,vbelakov/rstudio,pssguy/rstudio,sfloresm/rstudio,thklaus/rstudio,jrnold/rstudio,vbelakov/rstudio,maligulzar/Rstudio-instrumented,john-r-mcpherson/rstudio,sfloresm/rstudio,pssguy/rstudio,jzhu8803/rstudio,piersharding/rstudio,more1/rstudio,pssguy/rstudio,githubfun/rstudio,vbelakov/rstudio,jar1karp/rstudio,maligulzar/Rstudio-instrumented,piersharding/rstudio,maligulzar/Rstudio-instrumented,tbarrongh/rstudio,more1/rstudio,jzhu8803/rstudio,vbelakov/rstudio,jrnold/rstudio,vbelakov/rstudio,suribes/rstudio,thklaus/rstudio,nvoron23/rstudio,suribes/rstudio,JanMarvin/rstudio,more1/rstudio,tbarrongh/rstudio,tbarrongh/rstudio,vbelakov/rstudio,vbelakov/rstudio,jar1karp/rstudio,nvoron23/rstudio,JanMarvin/rstudio,brsimioni/rstudio,jrnold/rstudio,JanMarvin/rstudio,john-r-mcpherson/rstudio,thklaus/rstudio,jrnold/rstudio,sfloresm/rstudio,piersharding/rstudio,edrogers/rstudio,piersharding/rstudio,pssguy/rstudio,pssguy/rstudio,sfloresm/rstudio,jzhu8803/rstudio,piersharding/rstudio,jzhu8803/rstudio,piersharding/rstudio,jar1karp/rstudio,nvoron23/rstudio,jzhu8803/rstudio,tbarrongh/rstudio,edrogers/rstudio,thklaus/rstudio,JanMarvin/rstudio,pssguy/rstudio,nvoron23/rstudio,JanMarvin/rstudio,githubfun/rstudio,suribes/rstudio,tbarrongh/rstudio,githubfun/rstudio,JanMarvin/rstudio,pssguy/rstudio,brsimioni/rstudio,nvoron23/rstudio,maligulzar/Rstudio-instrumented,nvoron23/rstudio,john-r-mcpherson/rstudio,john-r-mcpherson/rstudio,brsimioni/rstudio,thklaus/rstudio,jzhu8803/rstudio,thklaus/rstudio,JanMarvin/rstudio,piersharding/rstudio,nvoron23/rstudio,brsimioni/rstudio,more1/rstudio,githubfun/rstudio,john-r-mcpherson/rstudio,githubfun/rstudio,maligulzar/Rstudio-instrumented,tbarrongh/rstudio,jar1karp/rstudio,sfloresm/rstudio,suribes/rstudio,more1/rstudio,suribes/rstudio,thklaus/rstudio,jrnold/rstudio,john-r-mcpherson/rstudio,jrnold/rstudio,maligulzar/Rstudio-instrumented,piersharding/rstudio,jrnold/rstudio,brsimioni/rstudio,jrnold/rstudio,pssguy/rstudio,sfloresm/rstudio,suribes/rstudio,more1/rstudio,jar1karp/rstudio,maligulzar/Rstudio-instrumented,jar1karp/rstudio,john-r-mcpherson/rstudio,edrogers/rstudio,brsimioni/rstudio,JanMarvin/rstudio,brsimioni/rstudio,JanMarvin/rstudio,more1/rstudio,jar1karp/rstudio,john-r-mcpherson/rstudio,edrogers/rstudio,tbarrongh/rstudio,edrogers/rstudio,sfloresm/rstudio,maligulzar/Rstudio-instrumented,suribes/rstudio,edrogers/rstudio,more1/rstudio,brsimioni/rstudio,maligulzar/Rstudio-instrumented,jar1karp/rstudio,tbarrongh/rstudio,jzhu8803/rstudio,vbelakov/rstudio,edrogers/rstudio,jar1karp/rstudio