Allow Actions to be initialized with a Scheduler
Allow Actions to be initialized with a Scheduler

An action will deliver results upon and synchronize itself with this
scheduler, allowing UI or background actions to be defined.

@robrix I decided against making this a type parameter, since the only
useful distinction (IMO) is background vs. not background, and that’s
not really captured in the Scheduler type family currently.

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a,natestedman/ReactiveCocoa,KJin99/ReactiveCocoa,jrmiddle/ReactiveCocoa,200895045/ReactiveCocoa,Pingco/ReactiveCocoa,libiao88/ReactiveCocoa,stevielu/ReactiveCocoa,msdgwzhy6/ReactiveCocoa,xiaobing2007/ReactiveCocoa,longv2go/ReactiveCocoa,ikesyo/ReactiveCocoa,alvinvarghese/ReactiveCocoa,leelili/ReactiveCocoa,dachaoisme/ReactiveCocoa,andersio/ReactiveCocoa,dullgrass/ReactiveCocoa,hilllinux/ReactiveCocoa,kevin-zqw/ReactiveCocoa,ioshger0125/ReactiveCocoa,OnTheWay1988/ReactiveCocoa,msdgwzhy6/ReactiveCocoa,dz1111/ReactiveCocoa,JohnJin007/ReactiveCocoa,libiao88/ReactiveCocoa,ceekayel/ReactiveCocoa,paulyoung/ReactiveCocoa,jam891/ReactiveCocoa,terry408911/ReactiveCocoa,natestedman/ReactiveCocoa,RuiAAPeres/ReactiveCocoa,xulibao/ReactiveCocoa,takeshineshiro/ReactiveCocoa,LHDsimon/ReactiveCocoa,hj3938/ReactiveCocoa,xiaoliyang/ReactiveCocoa,jeelun/ReactiveCocoa,add715/ReactiveCocoa,liufeigit/ReactiveCocoa,jrmiddle/ReactiveCocoa,Khan/ReactiveCocoa,howandhao/ReactiveCocoa,Ethan89/ReactiveCocoa,OnTheWay1988/ReactiveCocoa,yizzuide/ReactiveCocoa,ioshger0125/ReactiveCocoa,jeelun/ReactiveCocoa,CQXfly/ReactiveCocoa,zzqiltw/ReactiveCocoa,sdhzwm/ReactiveCocoa,AlanJN/ReactiveCocoa,DreamHill/ReactiveCocoa,ShawnLeee/ReactiveCocoa,paulyoung/ReactiveCocoa,ztchena/ReactiveCocoa,imkerberos/ReactiveCocoa,valleyman86/ReactiveCocoa,ioshger0125/ReactiveCocoa,bscarano/ReactiveCocoa,DongDongDongDong/ReactiveCocoa,itschaitanya/ReactiveCocoa,shuxiashusheng/ReactiveCocoa,alvinvarghese/ReactiveCocoa,yoichitgy/ReactiveCocoa,JackLian/ReactiveCocoa,vincentiss/ReactiveCocoa,hj3938/ReactiveCocoa,add715/ReactiveCocoa,Eveian/ReactiveCocoa,ohwutup/ReactiveCocoa,terry408911/ReactiveCocoa,towik/ReactiveCocoa,mtxs007/ReactiveCocoa,cnbin/ReactiveCocoa,mxxiv/ReactiveCocoa,esttorhe/ReactiveCocoa,wangqi211/ReactiveCocoa,esttorhe/ReactiveCocoa,dachaoisme/ReactiveCocoa,AndyZhaoHe/ReactiveCocoa,shuxiashusheng/ReactiveCocoa,qq644531343/ReactiveCocoa,icepy/ReactiveCocoa,howandhao/ReactiveCocoa,pzw224/ReactiveCocoa,windgo/ReactiveCocoa,zhaoguohui/ReactiveCocoa,juliangrosshauser/ReactiveCocoa,jeelun/ReactiveCocoa,bscarano/ReactiveCocoa,Ricowere/ReactiveCocoa,itschaitanya/ReactiveCocoa,zhigang1992/ReactiveCocoa,GuitarPlayer-Ma/ReactiveCocoa,kiurentu/ReactiveCocoa,bensonday/ReactiveCocoa,buildo/ReactiveCocoa,tzongw/ReactiveCocoa,zhukaixy/ReactiveCocoa,Khan/ReactiveCocoa,gengjf/ReactiveCocoa,JackLian/ReactiveCocoa,yytong/ReactiveCocoa,tiger8888/ReactiveCocoa,yangyangluoluo/ReactiveCocoa,nickcheng/ReactiveCocoa,hbucius/ReactiveCocoa,monkeydbobo/ReactiveCocoa,richeterre/ReactiveCocoa,Ethan89/ReactiveCocoa,KuPai32G/ReactiveCocoa,kevin-zqw/ReactiveCocoa,ddc391565320/ReactiveCocoa,hoanganh6491/ReactiveCocoa,eyu1988/ReactiveCocoa,jaylib/ReactiveCocoa,imkerberos/ReactiveCocoa,zzzworm/ReactiveCocoa,KuPai32G/ReactiveCocoa,kiurentu/ReactiveCocoa,victorlin/ReactiveCocoa,hilllinux/ReactiveCocoa,zxq3220122/ReactiveCocoa,wpstarnice/ReactiveCocoa,wangqi211/ReactiveCocoa,jsslai/ReactiveCocoa,huiping192/ReactiveCocoa,OnTheWay1988/ReactiveCocoa,CQXfly/ReactiveCocoa,SanChain/ReactiveCocoa,hilllinux/ReactiveCocoa,cnbin/ReactiveCocoa,monkeydbobo/ReactiveCocoa,CQXfly/ReactiveCocoa,goodheart/ReactiveCocoa,xumaolin/ReactiveCocoa,KJin99/ReactiveCocoa,leichunfeng/ReactiveCocoa,eyu1988/ReactiveCocoa,Ricowere/ReactiveCocoa,chao95957/ReactiveCocoa,sdhzwm/ReactiveCocoa,xiaobing2007/ReactiveCocoa,WEIBP/ReactiveCocoa,almassapargali/ReactiveCocoa,GuitarPlayer-Ma/ReactiveCocoa,ericzhou2008/ReactiveCocoa,yizzuide/ReactiveCocoa,beni55/ReactiveCocoa,tzongw/ReactiveCocoa,beni55/ReactiveCocoa,ddc391565320/ReactiveCocoa,andersio/ReactiveCocoa,leichunfeng/ReactiveCocoa,jackywpy/ReactiveCocoa,jam891/ReactiveCocoa,victorlin/ReactiveCocoa,pzw224/ReactiveCocoa,chieryw/ReactiveCocoa,ohwutup/ReactiveCocoa,nikita-leonov/ReactiveCocoa,Farteen/ReactiveCocoa,lixar/ReactiveCocoa,luerhouhou/ReactiveCocoa,fhchina/ReactiveCocoa,libiao88/ReactiveCocoa,takeshineshiro/ReactiveCocoa,taylormoonxu/ReactiveCocoa,isghe/ReactiveCocoa,longv2go/ReactiveCocoa,ceekayel/ReactiveCocoa,dz1111/ReactiveCocoa,gengjf/ReactiveCocoa,on99/ReactiveCocoa,Ray0218/ReactiveCocoa,j364960953/ReactiveCocoa,xiaobing2007/ReactiveCocoa,AndyZhaoHe/ReactiveCocoa,BrooksWon/ReactiveCocoa,xulibao/ReactiveCocoa,ikesyo/ReactiveCocoa,vincentiss/ReactiveCocoa,ztchena/ReactiveCocoa,richeterre/ReactiveCocoa,tonyarnold/ReactiveCocoa,FelixYin66/ReactiveCocoa,jaylib/ReactiveCocoa,almassapargali/ReactiveCocoa,chao95957/ReactiveCocoa,terry408911/ReactiveCocoa,lixar/ReactiveCocoa,shaohung001/ReactiveCocoa,jaylib/ReactiveCocoa,ericzhou2008/ReactiveCocoa,GuitarPlayer-Ma/ReactiveCocoa,juliangrosshauser/ReactiveCocoa,gengjf/ReactiveCocoa,tonyli508/ReactiveCocoa,Eveian/ReactiveCocoa,emodeqidao/ReactiveCocoa,LHDsimon/ReactiveCocoa,LHDsimon/ReactiveCocoa,huiping192/ReactiveCocoa,luerhouhou/ReactiveCocoa,cstars135/ReactiveCocoa,cnbin/ReactiveCocoa,Ricowere/ReactiveCocoa,jackywpy/ReactiveCocoa,Khan/ReactiveCocoa,taylormoonxu/ReactiveCocoa,yangyangluoluo/ReactiveCocoa,stevielu/ReactiveCocoa,zhukaixy/ReactiveCocoa,icepy/ReactiveCocoa,Liquidsoul/ReactiveCocoa,walkingsmarts/ReactiveCocoa,takeshineshiro/ReactiveCocoa,leichunfeng/ReactiveCocoa,j364960953/ReactiveCocoa,mattpetters/ReactiveCocoa,qq644531343/ReactiveCocoa,sujeking/ReactiveCocoa,ShawnLeee/ReactiveCocoa,rpowelll/ReactiveCocoa,jackywpy/ReactiveCocoa,fhchina/ReactiveCocoa,nikita-leonov/ReactiveCocoa,leelili/ReactiveCocoa,200895045/ReactiveCocoa,kiurentu/ReactiveCocoa,on99/ReactiveCocoa,icepy/ReactiveCocoa,clg0118/ReactiveCocoa,yaoxiaoyong/ReactiveCocoa,hoanganh6491/ReactiveCocoa,isghe/ReactiveCocoa,buildo/ReactiveCocoa,xumaolin/ReactiveCocoa,kaylio/ReactiveCocoa,beni55/ReactiveCocoa,natan/ReactiveCocoa,OneSmallTree/ReactiveCocoa,ceekayel/ReactiveCocoa,tonyarnold/ReactiveCocoa,sandyway/ReactiveCocoa,yonekawa/ReactiveCocoa,emodeqidao/ReactiveCocoa,Pingco/ReactiveCocoa,calebd/ReactiveCocoa,Ricowere/ReactiveCocoa,nickcheng/ReactiveCocoa,yangshengchaoios/ReactiveCocoa,cogddo/ReactiveCocoa,tonyli508/ReactiveCocoa,BrooksWon/ReactiveCocoa,dz1111/ReactiveCocoa,zhiwen1024/ReactiveCocoa,smilypeda/ReactiveCocoa,jsslai/ReactiveCocoa,bscarano/ReactiveCocoa,Juraldinio/ReactiveCocoa,natan/ReactiveCocoa,j364960953/ReactiveCocoa,mtxs007/ReactiveCocoa,nickcheng/ReactiveCocoa,stevielu/ReactiveCocoa,yonekawa/ReactiveCocoa,goodheart/ReactiveCocoa