fix(backbone): add Collection.add merge option (#9195)
fix(backbone): add Collection.add merge option (#9195)

This option is documented at http://backbonejs.org/#Collection-add.
tan9/DefinitelyTyped,smrq/DefinitelyTyped,benishouga/DefinitelyTyped,laurentiustamate94/DefinitelyTyped,emanuelhp/DefinitelyTyped,EnableSoftware/DefinitelyTyped,alvarorahul/DefinitelyTyped,HPFOD/DefinitelyTyped,benliddicott/DefinitelyTyped,nycdotnet/DefinitelyTyped,paulmorphy/DefinitelyTyped,alvarorahul/DefinitelyTyped,mareek/DefinitelyTyped,hellopao/DefinitelyTyped,raijinsetsu/DefinitelyTyped,YousefED/DefinitelyTyped,arusakov/DefinitelyTyped,DzmitryDulko/DefinitelyTyped,jraymakers/DefinitelyTyped,pocesar/DefinitelyTyped,shlomiassaf/DefinitelyTyped,YousefED/DefinitelyTyped,subash-a/DefinitelyTyped,psnider/DefinitelyTyped,AgentME/DefinitelyTyped,frogcjn/DefinitelyTyped,dsebastien/DefinitelyTyped,use-strict/DefinitelyTyped,mcrawshaw/DefinitelyTyped,Ptival/DefinitelyTyped,syuilo/DefinitelyTyped,AbraaoAlves/DefinitelyTyped,alexdresko/DefinitelyTyped,smrq/DefinitelyTyped,martinduparc/DefinitelyTyped,johan-gorter/DefinitelyTyped,progre/DefinitelyTyped,slavomirvojacek/adbrain-typescript-definitions,gandjustas/DefinitelyTyped,mattblang/DefinitelyTyped,axelcostaspena/DefinitelyTyped,syuilo/DefinitelyTyped,minodisk/DefinitelyTyped,micurs/DefinitelyTyped,daptiv/DefinitelyTyped,mattblang/DefinitelyTyped,aciccarello/DefinitelyTyped,pocesar/DefinitelyTyped,abner/DefinitelyTyped,rcchen/DefinitelyTyped,musicist288/DefinitelyTyped,amir-arad/DefinitelyTyped,slavomirvojacek/adbrain-typescript-definitions,borisyankov/DefinitelyTyped,EnableSoftware/DefinitelyTyped,nainslie/DefinitelyTyped,schmuli/DefinitelyTyped,mhegazy/DefinitelyTyped,ryan-codingintrigue/DefinitelyTyped,magny/DefinitelyTyped,jimthedev/DefinitelyTyped,arma-gast/DefinitelyTyped,frogcjn/DefinitelyTyped,psnider/DefinitelyTyped,martinduparc/DefinitelyTyped,xStrom/DefinitelyTyped,mareek/DefinitelyTyped,chrootsu/DefinitelyTyped,georgemarshall/DefinitelyTyped,georgemarshall/DefinitelyTyped,DzmitryDulko/DefinitelyTyped,GiedriusGrabauskas/DefinitelyTyped,scriby/DefinitelyTyped,AbraaoAlves/DefinitelyTyped,zuzusik/DefinitelyTyped,aciccarello/DefinitelyTyped,amanmahajan7/DefinitelyTyped,rcchen/DefinitelyTyped,hellopao/DefinitelyTyped,sledorze/DefinitelyTyped,schmuli/DefinitelyTyped,ashwinr/DefinitelyTyped,chrootsu/DefinitelyTyped,arusakov/DefinitelyTyped,benishouga/DefinitelyTyped,QuatroCode/DefinitelyTyped,chrismbarr/DefinitelyTyped,danfma/DefinitelyTyped,arusakov/DefinitelyTyped,mcrawshaw/DefinitelyTyped,shlomiassaf/DefinitelyTyped,johan-gorter/DefinitelyTyped,rolandzwaga/DefinitelyTyped,schmuli/DefinitelyTyped,Litee/DefinitelyTyped,emanuelhp/DefinitelyTyped,yuit/DefinitelyTyped,Ptival/DefinitelyTyped,psnider/DefinitelyTyped,mhegazy/DefinitelyTyped,GiedriusGrabauskas/DefinitelyTyped,Penryn/DefinitelyTyped,Zzzen/DefinitelyTyped,gcastre/DefinitelyTyped,donnut/DefinitelyTyped,HPFOD/DefinitelyTyped,sledorze/DefinitelyTyped,abbasmhd/DefinitelyTyped,hellopao/DefinitelyTyped,slavomirvojacek/DefinitelyTyped,gcastre/DefinitelyTyped,donnut/DefinitelyTyped,xStrom/DefinitelyTyped,stephenjelfs/DefinitelyTyped,mcliment/DefinitelyTyped,Litee/DefinitelyTyped,progre/DefinitelyTyped,gandjustas/DefinitelyTyped,markogresak/DefinitelyTyped,borisyankov/DefinitelyTyped,raijinsetsu/DefinitelyTyped,nycdotnet/DefinitelyTyped,Zzzen/DefinitelyTyped,nainslie/DefinitelyTyped,alexdresko/DefinitelyTyped,yuit/DefinitelyTyped,slavomirvojacek/DefinitelyTyped,isman-usoh/DefinitelyTyped,damianog/DefinitelyTyped,benishouga/DefinitelyTyped,use-strict/DefinitelyTyped,abner/DefinitelyTyped,jimthedev/DefinitelyTyped,rolandzwaga/DefinitelyTyped,dsebastien/DefinitelyTyped,abbasmhd/DefinitelyTyped,aciccarello/DefinitelyTyped,isman-usoh/DefinitelyTyped,danfma/DefinitelyTyped,tan9/DefinitelyTyped,scriby/DefinitelyTyped,AgentME/DefinitelyTyped,amanmahajan7/DefinitelyTyped,martinduparc/DefinitelyTyped,zuzusik/DefinitelyTyped,AgentME/DefinitelyTyped,chbrown/DefinitelyTyped,jimthedev/DefinitelyTyped,florentpoujol/DefinitelyTyped,damianog/DefinitelyTyped,florentpoujol/DefinitelyTyped,jraymakers/DefinitelyTyped,one-pieces/DefinitelyTyped,Penryn/DefinitelyTyped,georgemarshall/DefinitelyTyped,stephenjelfs/DefinitelyTyped,AgentME/DefinitelyTyped,zuzusik/DefinitelyTyped,chrismbarr/DefinitelyTyped,georgemarshall/DefinitelyTyped,minodisk/DefinitelyTyped,arma-gast/DefinitelyTyped,pocesar/DefinitelyTyped,AbraaoAlves/DefinitelyTyped,magny/DefinitelyTyped,paulmorphy/DefinitelyTyped,subash-a/DefinitelyTyped,newclear/DefinitelyTyped,ashwinr/DefinitelyTyped,newclear/DefinitelyTyped,QuatroCode/DefinitelyTyped