Prevent undo/redo from working in readOnly mode
Prevent undo/redo from working in readOnly mode

Closes #1369

mtaran-google/CodeMirror,bocharsky-bw/CodeMirror,thomasjm/CodeMirror,sanyaade-iot/CodeMirror,flyskyko/CodeMirror,pabloferz/CodeMirror,grzegorzmazur/CodeMirror,dudb/CodeMirror,fpco/codemirror,djadmin/CodeMirror,bfrohs/CodeMirror,xeronith/CodeMirror,sekcheong/CodeMirror,codio/CodeMirror,TDaglis/CodeMirror,Jisuanke/CodeMirror,abdelouahabb/CodeMirror,schanzer/CodeMirror,angelozerr/CodeMirror,rrandom/CodeMirror,thomasjm/CodeMirror,ssxxue/CodeMirror,fmoliveira/CodeMirror,jochenberger/CodeMirror,kk9599/CodeMirror,davidpham87/CodeMirror,wbinnssmith/CodeMirror,mightyguava/CodeMirror,nightwing/CodeMirror,axter/CodeMirror,TechnicalPursuit/CodeMirror,apatawari/CodeMirror,matthewbauer/CodeMirror,agendor/CodeMirror,MarcelGerber/CodeMirror,Aliccer/CodeMirror,loopspace/CodeMirror,flyskyko/CodeMirror,grzegorzmazur/CodeMirror,MarcelGerber/CodeMirror,NumbersInternational/CodeMirror,vanloswang/CodeMirror,Ermlab/CodeMirror,dperetti/CodeMirror,r7kamura/CodeMirror,kevinushey/CodeMirror,abdelouahabb/CodeMirror,kk9599/CodeMirror,mightyguava/CodeMirror,ksanaforge/CodeMirror,ZombieHippie/CodeMirror,karevn/CodeMirror,dperetti/CodeMirror,pjkui/CodeMirror,alur/CodeMirror,ficristo/CodeMirror,belph/CodeMirror,philuchansky/CodeMirror,NeZaMy/CodeMirror2,ejgallego/CodeMirror,nawroth/CodeMirror,jayaprabhakar/CodeMirror,DustinH/CodeMirror,SidPresse/CodeMirror,Navaneethsen/CodeMirror,MarcelGerber/CodeMirror,kerabromsmu/CodeMirror,camellhf/CodeMirror,camellhf/CodeMirror,amshali/CodeMirror,namin/CodeMirror,NumbersInternational/CodeMirror,ThebingServices/CodeMirror,jkaplon/CodeMirror,buchslava/CodeMirror,kangkot/CodeMirror,rasata/CodeMirror,crazy4chrissi/CodeMirror,Dominator008/CodeMirror,kuangyeheng/CodeMirror,nawroth/CodeMirror,jkaplon/CodeMirror,happibum/CodeMirror-main,manderson23/CodeMirror,hccampos/CodeMirror,ksanaforge/CodeMirror,joshterrell805-historic/CodeMirror,ssxxue/CodeMirror,elisee/CodeMirror,nightwing/CodeMirror,vincentwoo/CodeMirror,rustemferreira/CodeMirror,amsul/CodeMirror,dperetti/CodeMirror,Navaneethsen/CodeMirror,notepadqq/CodeMirror,bluesh55/CodeMirror,jhnesk/CodeMirror,djadmin/CodeMirror,cben/CodeMirror,rustemferreira/CodeMirror,karthikeyansam/CodeMirror,Carreau/CodeMirror,jessegrosjean/CodeMirror,NeZaMy/CodeMirror2,dudb/CodeMirror,fivetran/CodeMirror,GerHobbelt/CodeMirror2,xeronith/CodeMirror,r7kamura/CodeMirror,adobe/CodeMirror2,fpco/codemirror,CartoDB/CodeMirror,wingify/CodeMirror,bocharsky-bw/CodeMirror,buchslava/CodeMirror,systay/CodeMirror,jayaprabhakar/CodeMirror,notepadqq/CodeMirror,apatawari/CodeMirror,sekcheong/CodeMirror,EasonYi/CodeMirror,jhnesk/CodeMirror,Navaneethsen/CodeMirror,rrandom/CodeMirror,webida/CodeMirror,loopspace/CodeMirror,wbinnssmith/CodeMirror,mtaran-google/CodeMirror,anthonygego/CodeMirror,ejgallego/CodeMirror,Ermlab/CodeMirror,qweasd1/CodeMirror,AlanWasTaken/codemirror,schanzer/CodeMirror,TechnicalPursuit/CodeMirror,amshali/CodeMirror,codio/CodeMirror,vanloswang/CodeMirror,pabloferz/CodeMirror,kangkot/CodeMirror,cintiamh/CodeMirror,namin/CodeMirror,InternetGuru/CodeMirror,d0liver/CodeMirror,pjkui/CodeMirror,ashmind/CodeMirror,hackmdio/CodeMirror,webida/CodeMirror,TDaglis/CodeMirror,tpphu/CodeMirror,buchslava/CodeMirror,davidpham87/CodeMirror,kk9599/CodeMirror,InternetGuru/CodeMirror,adobe/CodeMirror2,KamranMackey/CodeMirror,schanzer/CodeMirror,gkoberger/CodeMirror,kuangyeheng/CodeMirror,SidPresse/CodeMirror,sanyaade-iot/CodeMirror,melpon/CodeMirror,jpolitz/CodeMirror,tpphu/CodeMirror,axter/CodeMirror,elisee/CodeMirror,ZombieHippie/CodeMirror,jansel/CodeMirror,Aliccer/CodeMirror,gkoberger/CodeMirror,anthonygego/CodeMirror,bluesh55/CodeMirror,pinbe/CodeMirror,supriyantomaftuh/CodeMirror,isdampe/CodeMirror,d0liver/CodeMirror,r7kamura/CodeMirror,amsul/CodeMirror,bocharsky-bw/CodeMirror,cben/CodeMirror,grzegorzmazur/CodeMirror,kolya-ay/CodeMirror,kangkot/CodeMirror,belph/CodeMirror,supriyantomaftuh/CodeMirror,systay/CodeMirror,amshali/CodeMirror,namin/CodeMirror,shiren/CodeMirror,davidpham87/CodeMirror,qiankun007/CodeMirror,nightwing/CodeMirror,hackmdio/CodeMirror,Icenium/CodeMirror,trumanliu/CodeMirror,bgrins/CodeMirror,cintiamh/CodeMirror,axter/CodeMirror,ficristo/CodeMirror,morrisonwudi/CodeMirror,trumanliu/CodeMirror,thomasjm/CodeMirror,ashmind/CodeMirror,abdelouahabb/CodeMirror,elisee/CodeMirror,rasata/CodeMirror,shiren/CodeMirror,Dominator008/CodeMirror,alur/CodeMirror,mightyguava/CodeMirror,DustinH/CodeMirror,matthewbauer/CodeMirror,mtaran-google/CodeMirror,hccampos/CodeMirror,qweasd1/CodeMirror,EasonYi/CodeMirror,belph/CodeMirror,KamranMackey/CodeMirror,kuangyeheng/CodeMirror,jkaplon/CodeMirror,philuchansky/CodeMirror,dbarnett/CodeMirror,pinbe/CodeMirror,d0liver/CodeMirror,INTELOGIE/CodeMirror,isdampe/CodeMirror,morrisonwudi/CodeMirror,pjkui/CodeMirror,Jisuanke/CodeMirror,kevinushey/CodeMirror,antimatter15/CodeMirror,INTELOGIE/CodeMirror,TechnicalPursuit/CodeMirror,increpare/CodeMirror,gkoberger/CodeMirror,dbarnett/CodeMirror,increpare/CodeMirror,TDaglis/CodeMirror,KamranMackey/CodeMirror,ThebingServices/CodeMirror,fmoliveira/CodeMirror,karthikeyansam/CodeMirror,michaelerobertsjr/CodeMirror,Carreau/CodeMirror,xeronith/CodeMirror,tpphu/CodeMirror,ssxxue/CodeMirror,karthikeyansam/CodeMirror,Allenice/CodeMirror,sourcelair/CodeMirror,crazy4chrissi/CodeMirror,CartoDB/CodeMirror,kerabromsmu/CodeMirror,skylarkcob/CodeMirror,Jisuanke/CodeMirror,INTELOGIE/CodeMirror,flyskyko/CodeMirror,isdampe/CodeMirror,codio/CodeMirror,joshterrell805-historic/CodeMirror,Dominator008/CodeMirror,dudb/CodeMirror,karevn/CodeMirror,antimatter15/CodeMirror,djadmin/CodeMirror,AlanWasTaken/codemirror,sourcelair/CodeMirror,ficristo/CodeMirror,apatawari/CodeMirror,symbla/CodeMirror,mizchi/CodeMirror,SidPresse/CodeMirror,symbla/CodeMirror,bluesh55/CodeMirror,manderson23/CodeMirror,michaelerobertsjr/CodeMirror,mihailik/CodeMirror,systay/CodeMirror,rrandom/CodeMirror,Icenium/CodeMirror,sgoo/CodeMirror,cintiamh/CodeMirror,vincentwoo/CodeMirror,increpare/CodeMirror,mihailik/CodeMirror,jpolitz/CodeMirror,GerHobbelt/CodeMirror2,webida/CodeMirror,bfrohs/CodeMirror,angelozerr/CodeMirror,DustinH/CodeMirror,NumbersInternational/CodeMirror,jessegrosjean/CodeMirror,manderson23/CodeMirror,antimatter15/CodeMirror,jochenberger/CodeMirror,vanloswang/CodeMirror,jansel/CodeMirror,pabloferz/CodeMirror,supriyantomaftuh/CodeMirror,adobe/CodeMirror2,qiankun007/CodeMirror,InternetGuru/CodeMirror,bfrohs/CodeMirror,jpolitz/CodeMirror,ThebingServices/CodeMirror,sourcelair/CodeMirror,shiren/CodeMirror,ksanaforge/CodeMirror,ZombieHippie/CodeMirror,trumanliu/CodeMirror,kerabromsmu/CodeMirror,fmoliveira/CodeMirror,pinbe/CodeMirror,ejgallego/CodeMirror,sgoo/CodeMirror,EasonYi/CodeMirror,Allenice/CodeMirror,matthewbauer/CodeMirror,bgrins/CodeMirror,michaelerobertsjr/CodeMirror,symbla/CodeMirror,mihailik/CodeMirror,vincentwoo/CodeMirror,morrisonwudi/CodeMirror,ashmind/CodeMirror,bgrins/CodeMirror,loopspace/CodeMirror,crazy4chrissi/CodeMirror,agendor/CodeMirror,jessegrosjean/CodeMirror,Icenium/CodeMirror,happibum/CodeMirror-main,sekcheong/CodeMirror,notepadqq/CodeMirror,AlanWasTaken/codemirror,melpon/CodeMirror,mizchi/CodeMirror,sanyaade-iot/CodeMirror,wingify/CodeMirror,camellhf/CodeMirror,hccampos/CodeMirror,philuchansky/CodeMirror,skylarkcob/CodeMirror,NeZaMy/CodeMirror2,agendor/CodeMirror,Allenice/CodeMirror,alur/CodeMirror,rustemferreira/CodeMirror,kolya-ay/CodeMirror,rasata/CodeMirror,jayaprabhakar/CodeMirror,melpon/CodeMirror,Aliccer/CodeMirror,wingify/CodeMirror,qweasd1/CodeMirror,karevn/CodeMirror,webida/CodeMirror,hackmdio/CodeMirror,dbarnett/CodeMirror,nawroth/CodeMirror,anthonygego/CodeMirror,fivetran/CodeMirror,skylarkcob/CodeMirror,mizchi/CodeMirror,happibum/CodeMirror-main,qiankun007/CodeMirror