[gfm mode] Define a MIME, remove bogus use of defineMIME
[gfm mode] Define a MIME, remove bogus use of defineMIME

Closes #3345

ksanaforge/CodeMirror,buchslava/CodeMirror,adobe/CodeMirror2,ZombieHippie/CodeMirror,TDaglis/CodeMirror,rrandom/CodeMirror,mihailik/CodeMirror,Allenice/CodeMirror,notepadqq/CodeMirror,rrandom/CodeMirror,thomasjm/CodeMirror,supriyantomaftuh/CodeMirror,r7kamura/CodeMirror,grzegorzmazur/CodeMirror,rrandom/CodeMirror,kerabromsmu/CodeMirror,crazy4chrissi/CodeMirror,MarcelGerber/CodeMirror,dperetti/CodeMirror,karevn/CodeMirror,apatawari/CodeMirror,dudb/CodeMirror,hccampos/CodeMirror,davidpham87/CodeMirror,symbla/CodeMirror,dperetti/CodeMirror,anthonygego/CodeMirror,codio/CodeMirror,Allenice/CodeMirror,mizchi/CodeMirror,NumbersInternational/CodeMirror,bocharsky-bw/CodeMirror,camellhf/CodeMirror,Aliccer/CodeMirror,d0liver/CodeMirror,philuchansky/CodeMirror,camellhf/CodeMirror,vincentwoo/CodeMirror,jayaprabhakar/CodeMirror,INTELOGIE/CodeMirror,ashmind/CodeMirror,DustinH/CodeMirror,notepadqq/CodeMirror,qiankun007/CodeMirror,karthikeyansam/CodeMirror,ThebingServices/CodeMirror,INTELOGIE/CodeMirror,matthewbauer/CodeMirror,systay/CodeMirror,skylarkcob/CodeMirror,supriyantomaftuh/CodeMirror,Jisuanke/CodeMirror,melpon/CodeMirror,EasonYi/CodeMirror,sourcelair/CodeMirror,shiren/CodeMirror,morrisonwudi/CodeMirror,EasonYi/CodeMirror,jkaplon/CodeMirror,nightwing/CodeMirror,namin/CodeMirror,qweasd1/CodeMirror,pabloferz/CodeMirror,InternetGuru/CodeMirror,alur/CodeMirror,karevn/CodeMirror,rasata/CodeMirror,sekcheong/CodeMirror,ficristo/CodeMirror,TechnicalPursuit/CodeMirror,d0liver/CodeMirror,bfrohs/CodeMirror,ssxxue/CodeMirror,agendor/CodeMirror,bocharsky-bw/CodeMirror,kk9599/CodeMirror,dperetti/CodeMirror,philuchansky/CodeMirror,NumbersInternational/CodeMirror,rasata/CodeMirror,skylarkcob/CodeMirror,codio/CodeMirror,manderson23/CodeMirror,tpphu/CodeMirror,pabloferz/CodeMirror,increpare/CodeMirror,karthikeyansam/CodeMirror,kangkot/CodeMirror,Allenice/CodeMirror,mtaran-google/CodeMirror,ksanaforge/CodeMirror,jessegrosjean/CodeMirror,matthewbauer/CodeMirror,SidPresse/CodeMirror,ficristo/CodeMirror,Navaneethsen/CodeMirror,MarcelGerber/CodeMirror,qweasd1/CodeMirror,ashmind/CodeMirror,vanloswang/CodeMirror,kerabromsmu/CodeMirror,melpon/CodeMirror,ssxxue/CodeMirror,sourcelair/CodeMirror,mihailik/CodeMirror,codio/CodeMirror,buchslava/CodeMirror,TechnicalPursuit/CodeMirror,r7kamura/CodeMirror,shiren/CodeMirror,pjkui/CodeMirror,cintiamh/CodeMirror,mtaran-google/CodeMirror,michaelerobertsjr/CodeMirror,jessegrosjean/CodeMirror,tpphu/CodeMirror,Aliccer/CodeMirror,kk9599/CodeMirror,sekcheong/CodeMirror,pinbe/CodeMirror,wingify/CodeMirror,hackmdio/CodeMirror,davidpham87/CodeMirror,symbla/CodeMirror,happibum/CodeMirror-main,davidpham87/CodeMirror,adobe/CodeMirror2,Navaneethsen/CodeMirror,nightwing/CodeMirror,dudb/CodeMirror,TDaglis/CodeMirror,bfrohs/CodeMirror,grzegorzmazur/CodeMirror,mizchi/CodeMirror,fmoliveira/CodeMirror,tpphu/CodeMirror,kuangyeheng/CodeMirror,increpare/CodeMirror,EasonYi/CodeMirror,jessegrosjean/CodeMirror,isdampe/CodeMirror,djadmin/CodeMirror,rasata/CodeMirror,agendor/CodeMirror,alur/CodeMirror,michaelerobertsjr/CodeMirror,ejgallego/CodeMirror,mizchi/CodeMirror,hccampos/CodeMirror,anthonygego/CodeMirror,melpon/CodeMirror,DustinH/CodeMirror,sourcelair/CodeMirror,symbla/CodeMirror,systay/CodeMirror,wingify/CodeMirror,d0liver/CodeMirror,michaelerobertsjr/CodeMirror,cintiamh/CodeMirror,SidPresse/CodeMirror,kk9599/CodeMirror,kuangyeheng/CodeMirror,axter/CodeMirror,TDaglis/CodeMirror,SidPresse/CodeMirror,amshali/CodeMirror,schanzer/CodeMirror,namin/CodeMirror,kerabromsmu/CodeMirror,bgrins/CodeMirror,jkaplon/CodeMirror,vanloswang/CodeMirror,amshali/CodeMirror,schanzer/CodeMirror,adobe/CodeMirror2,morrisonwudi/CodeMirror,MarcelGerber/CodeMirror,happibum/CodeMirror-main,nawroth/CodeMirror,pabloferz/CodeMirror,hackmdio/CodeMirror,notepadqq/CodeMirror,morrisonwudi/CodeMirror,Jisuanke/CodeMirror,sanyaade-iot/CodeMirror,increpare/CodeMirror,dudb/CodeMirror,axter/CodeMirror,ashmind/CodeMirror,ksanaforge/CodeMirror,supriyantomaftuh/CodeMirror,ficristo/CodeMirror,skylarkcob/CodeMirror,ejgallego/CodeMirror,ssxxue/CodeMirror,crazy4chrissi/CodeMirror,r7kamura/CodeMirror,djadmin/CodeMirror,bgrins/CodeMirror,ThebingServices/CodeMirror,pinbe/CodeMirror,Dominator008/CodeMirror,buchslava/CodeMirror,qweasd1/CodeMirror,TechnicalPursuit/CodeMirror,sanyaade-iot/CodeMirror,Dominator008/CodeMirror,InternetGuru/CodeMirror,qiankun007/CodeMirror,mtaran-google/CodeMirror,ThebingServices/CodeMirror,pjkui/CodeMirror,kuangyeheng/CodeMirror,sanyaade-iot/CodeMirror,DustinH/CodeMirror,kangkot/CodeMirror,pjkui/CodeMirror,INTELOGIE/CodeMirror,camellhf/CodeMirror,antimatter15/CodeMirror,trumanliu/CodeMirror,fmoliveira/CodeMirror,anthonygego/CodeMirror,schanzer/CodeMirror,axter/CodeMirror,ejgallego/CodeMirror,loopspace/CodeMirror,matthewbauer/CodeMirror,fmoliveira/CodeMirror,antimatter15/CodeMirror,loopspace/CodeMirror,nawroth/CodeMirror,sekcheong/CodeMirror,Navaneethsen/CodeMirror,happibum/CodeMirror-main,InternetGuru/CodeMirror,cintiamh/CodeMirror,Dominator008/CodeMirror,nawroth/CodeMirror,crazy4chrissi/CodeMirror,nightwing/CodeMirror,agendor/CodeMirror,jayaprabhakar/CodeMirror,trumanliu/CodeMirror,djadmin/CodeMirror,hackmdio/CodeMirror,NumbersInternational/CodeMirror,bfrohs/CodeMirror,alur/CodeMirror,grzegorzmazur/CodeMirror,jkaplon/CodeMirror,hccampos/CodeMirror,manderson23/CodeMirror,systay/CodeMirror,apatawari/CodeMirror,ZombieHippie/CodeMirror,vanloswang/CodeMirror,thomasjm/CodeMirror,antimatter15/CodeMirror,namin/CodeMirror,Aliccer/CodeMirror,karevn/CodeMirror,manderson23/CodeMirror,karthikeyansam/CodeMirror,amshali/CodeMirror,ZombieHippie/CodeMirror,mihailik/CodeMirror,Jisuanke/CodeMirror,kangkot/CodeMirror,wingify/CodeMirror,philuchansky/CodeMirror,xeronith/CodeMirror,isdampe/CodeMirror,vincentwoo/CodeMirror,vincentwoo/CodeMirror,qiankun007/CodeMirror,apatawari/CodeMirror,isdampe/CodeMirror,xeronith/CodeMirror,xeronith/CodeMirror,pinbe/CodeMirror,trumanliu/CodeMirror,thomasjm/CodeMirror,jayaprabhakar/CodeMirror,bocharsky-bw/CodeMirror,bgrins/CodeMirror,shiren/CodeMirror,loopspace/CodeMirror