Implement -[RACSignal bind:] from scratch, without -flatten:
Implement -[RACSignal bind:] from scratch, without -flatten:

The resulting combined logic should be easier to follow and fix.

Conflicts:
	ReactiveCocoaFramework/ReactiveCocoa/RACSignal.m

CQXfly/ReactiveCocoa,SuPair/ReactiveCocoa,gabemdev/ReactiveCocoa,zzqiltw/ReactiveCocoa,Farteen/ReactiveCocoa,Pingco/ReactiveCocoa,AndyZhaoHe/ReactiveCocoa,ztchena/ReactiveCocoa,kaylio/ReactiveCocoa,wpstarnice/ReactiveCocoa,dz1111/ReactiveCocoa,natan/ReactiveCocoa,FelixYin66/ReactiveCocoa,LHDsimon/ReactiveCocoa,Adlai-Holler/ReactiveCocoa,AlanJN/ReactiveCocoa,walkingsmarts/ReactiveCocoa,fhchina/ReactiveCocoa,AlanJN/ReactiveCocoa,almassapargali/ReactiveCocoa,DreamHill/ReactiveCocoa,ericzhou2008/ReactiveCocoa,nickcheng/ReactiveCocoa,valleyman86/ReactiveCocoa,lixar/ReactiveCocoa,hj3938/ReactiveCocoa,Remitly/ReactiveCocoa,jaylib/ReactiveCocoa,zhukaixy/ReactiveCocoa,mtxs007/ReactiveCocoa,monkeydbobo/ReactiveCocoa,ceekayel/ReactiveCocoa,msdgwzhy6/ReactiveCocoa,juliangrosshauser/ReactiveCocoa,liufeigit/ReactiveCocoa,cstars135/ReactiveCocoa,xiaoliyang/ReactiveCocoa,JohnJin007/ReactiveCocoa,DongDongDongDong/ReactiveCocoa,isghe/ReactiveCocoa,koamac/ReactiveCocoa,victorlin/ReactiveCocoa,xulibao/ReactiveCocoa,Juraldinio/ReactiveCocoa,yytong/ReactiveCocoa,on99/ReactiveCocoa,KuPai32G/ReactiveCocoa,leelili/ReactiveCocoa,jianwoo/ReactiveCocoa,LHDsimon/ReactiveCocoa,icepy/ReactiveCocoa,towik/ReactiveCocoa,natan/ReactiveCocoa,tonyli508/ReactiveCocoa,jaylib/ReactiveCocoa,hbucius/ReactiveCocoa,tornade0913/ReactiveCocoa,Remitly/ReactiveCocoa,KJin99/ReactiveCocoa,yangyangluoluo/ReactiveCocoa,bencochran/ReactiveCocoa,qq644531343/ReactiveCocoa,cogddo/ReactiveCocoa,eyu1988/ReactiveCocoa,OnTheWay1988/ReactiveCocoa,msdgwzhy6/ReactiveCocoa,zhukaixy/ReactiveCocoa,llb1119/test,Liquidsoul/ReactiveCocoa,JackLian/ReactiveCocoa,mxxiv/ReactiveCocoa,llb1119/test,huiping192/ReactiveCocoa,bencochran/ReactiveCocoa,eyu1988/ReactiveCocoa,xumaolin/ReactiveCocoa,tonyli508/ReactiveCocoa,alvinvarghese/ReactiveCocoa,goodheart/ReactiveCocoa,FelixYin66/ReactiveCocoa,brightcove/ReactiveCocoa,jackywpy/ReactiveCocoa,chieryw/ReactiveCocoa,huiping192/ReactiveCocoa,Pingco/ReactiveCocoa,Juraldinio/ReactiveCocoa,msdgwzhy6/ReactiveCocoa,liufeigit/ReactiveCocoa,stevielu/ReactiveCocoa,dskatz22/ReactiveCocoa,jsslai/ReactiveCocoa,nikita-leonov/ReactiveCocoa,wangqi211/ReactiveCocoa,takeshineshiro/ReactiveCocoa,paulyoung/ReactiveCocoa,chao95957/ReactiveCocoa,esttorhe/ReactiveCocoa,sujeking/ReactiveCocoa,ztchena/ReactiveCocoa,ztchena/ReactiveCocoa,SmartEncounter/ReactiveCocoa,Ethan89/ReactiveCocoa,ohwutup/ReactiveCocoa,fhchina/ReactiveCocoa,fanghao085/ReactiveCocoa,wangqi211/ReactiveCocoa,leichunfeng/ReactiveCocoa,koamac/ReactiveCocoa,tzongw/ReactiveCocoa,sdhzwm/ReactiveCocoa,BrooksWon/ReactiveCocoa,BlessNeo/ReactiveCocoa,dachaoisme/ReactiveCocoa,OnTheWay1988/ReactiveCocoa,kevin-zqw/ReactiveCocoa,fanghao085/ReactiveCocoa,zhigang1992/ReactiveCocoa,buildo/ReactiveCocoa,OnTheWay1988/ReactiveCocoa,Rupert-RR/ReactiveCocoa,swizzlr/ReactiveCocoa,esttorhe/ReactiveCocoa,WEIBP/ReactiveCocoa,bensonday/ReactiveCocoa,SuPair/ReactiveCocoa,dullgrass/ReactiveCocoa,stupidfive/ReactiveCocoa,eyu1988/ReactiveCocoa,AllanChen/ReactiveCocoa,yytong/ReactiveCocoa,Liquidsoul/ReactiveCocoa,xumaolin/ReactiveCocoa,mattpetters/ReactiveCocoa,goodheart/ReactiveCocoa,natestedman/ReactiveCocoa,Ethan89/ReactiveCocoa,cnbin/ReactiveCocoa,yizzuide/ReactiveCocoa,luerhouhou/ReactiveCocoa,BrooksWon/ReactiveCocoa,KJin99/ReactiveCocoa,yangshengchaoios/ReactiveCocoa,Khan/ReactiveCocoa,yaoxiaoyong/ReactiveCocoa,yizzuide/ReactiveCocoa,CCOOOOLL/ReactiveCocoa,natestedman/ReactiveCocoa,gengjf/ReactiveCocoa,rpowelll/ReactiveCocoa,loupman/ReactiveCocoa,Ray0218/ReactiveCocoa,tonyarnold/ReactiveCocoa,jam891/ReactiveCocoa,natan/ReactiveCocoa,natestedman/ReactiveCocoa,zhiwen1024/ReactiveCocoa,335g/ReactiveCocoa,bensonday/ReactiveCocoa,Carthage/ReactiveCocoa,nickcheng/ReactiveCocoa,huiping192/ReactiveCocoa,dz1111/ReactiveCocoa,calebd/ReactiveCocoa,calebd/ReactiveCocoa,jianwoo/ReactiveCocoa,zzzworm/ReactiveCocoa,richeterre/ReactiveCocoa,hj3938/ReactiveCocoa,zxq3220122/ReactiveCocoa,chieryw/ReactiveCocoa,leelili/ReactiveCocoa,jsslai/ReactiveCocoa,kiurentu/ReactiveCocoa,eliperkins/ReactiveCocoa,hoanganh6491/ReactiveCocoa,shuxiashusheng/ReactiveCocoa,sdhzwm/ReactiveCocoa,liufeigit/ReactiveCocoa,zhiwen1024/ReactiveCocoa,ShawnLeee/ReactiveCocoa,fhchina/ReactiveCocoa,335g/ReactiveCocoa,ReactiveCocoa/ReactiveSwift,SanChain/ReactiveCocoa,fanghao085/ReactiveCocoa,lixar/ReactiveCocoa,ioshger0125/ReactiveCocoa,mattpetters/ReactiveCocoa,ailyanlu/ReactiveCocoa,walkingsmarts/ReactiveCocoa,dachaoisme/ReactiveCocoa,ShawnLeee/ReactiveCocoa,200895045/ReactiveCocoa,ddc391565320/ReactiveCocoa,zhigang1992/ReactiveCocoa,Farteen/ReactiveCocoa,beni55/ReactiveCocoa,zhaoguohui/ReactiveCocoa,llb1119/test,beni55/ReactiveCocoa,terry408911/ReactiveCocoa,Khan/ReactiveCocoa,AllanChen/ReactiveCocoa,taylormoonxu/ReactiveCocoa,walkingsmarts/ReactiveCocoa,OneSmallTree/ReactiveCocoa,sugar2010/ReactiveCocoa,Rupert-RR/ReactiveCocoa,ailyanlu/ReactiveCocoa,j364960953/ReactiveCocoa,yonekawa/ReactiveCocoa,JohnJin007/ReactiveCocoa,dachaoisme/ReactiveCocoa,zhiwen1024/ReactiveCocoa,pzw224/ReactiveCocoa,cnbin/ReactiveCocoa,libiao88/ReactiveCocoa,bscarano/ReactiveCocoa,Pikdays/ReactiveCocoa,windgo/ReactiveCocoa,hilllinux/ReactiveCocoa,eliperkins/ReactiveCocoa,kaylio/ReactiveCocoa,on99/ReactiveCocoa,howandhao/ReactiveCocoa,yoichitgy/ReactiveCocoa,BrooksWon/ReactiveCocoa,tonyli508/ReactiveCocoa,OneSmallTree/ReactiveCocoa,dz1111/ReactiveCocoa,longv2go/ReactiveCocoa,buildo/ReactiveCocoa,RuiAAPeres/ReactiveCocoa,RuiAAPeres/ReactiveCocoa,mxxiv/ReactiveCocoa,zzqiltw/ReactiveCocoa,tiger8888/ReactiveCocoa,DreamHill/ReactiveCocoa,imkerberos/ReactiveCocoa,Ricowere/ReactiveCocoa,terry408911/ReactiveCocoa,CQXfly/ReactiveCocoa,sandyway/ReactiveCocoa,stupidfive/ReactiveCocoa,ShawnLeee/ReactiveCocoa,Eveian/ReactiveCocoa,paulyoung/ReactiveCocoa,zhenlove/ReactiveCocoa,hbucius/ReactiveCocoa,smilypeda/ReactiveCocoa,dullgrass/ReactiveCocoa,emodeqidao/ReactiveCocoa,tzongw/ReactiveCocoa,Pikdays/ReactiveCocoa,yangshengchaoios/ReactiveCocoa,brasbug/ReactiveCocoa,GuitarPlayer-Ma/ReactiveCocoa,Eveian/ReactiveCocoa,ailyanlu/ReactiveCocoa,wpstarnice/ReactiveCocoa,Ray0218/ReactiveCocoa,sdhzwm/ReactiveCocoa,on99/ReactiveCocoa,yangyangluoluo/ReactiveCocoa,SanChain/ReactiveCocoa,xiaobing2007/ReactiveCocoa,monkeydbobo/ReactiveCocoa,ceekayel/ReactiveCocoa,jaylib/ReactiveCocoa,brightcove/ReactiveCocoa,brasbug/ReactiveCocoa,yonekawa/ReactiveCocoa,longv2go/ReactiveCocoa,jam891/ReactiveCocoa,cogddo/ReactiveCocoa,ikesyo/ReactiveCocoa,Eveian/ReactiveCocoa,WEIBP/ReactiveCocoa,ceekayel/ReactiveCocoa,valleyman86/ReactiveCocoa,jeelun/ReactiveCocoa,tornade0913/ReactiveCocoa,brightcove/ReactiveCocoa,kevin-zqw/ReactiveCocoa,huiping192/ReactiveCocoa,leichunfeng/ReactiveCocoa,alvinvarghese/ReactiveCocoa,Carthage/ReactiveCocoa,sujeking/ReactiveCocoa,mtxs007/ReactiveCocoa,icepy/ReactiveCocoa,dskatz22/ReactiveCocoa,shuxiashusheng/ReactiveCocoa,JackLian/ReactiveCocoa,Ricowere/ReactiveCocoa,Ricowere/ReactiveCocoa,zhenlove/ReactiveCocoa,nickcheng/ReactiveCocoa,Ricowere/ReactiveCocoa,zhukaixy/ReactiveCocoa,taylormoonxu/ReactiveCocoa,chao95957/ReactiveCocoa,goodheart/ReactiveCocoa,Ray0218/ReactiveCocoa,JackLian/ReactiveCocoa,wpstarnice/ReactiveCocoa,CCOOOOLL/ReactiveCocoa,cnbin/ReactiveCocoa,calebd/ReactiveCocoa,howandhao/ReactiveCocoa,smilypeda/ReactiveCocoa,yoichitgy/ReactiveCocoa,bencochran/ReactiveCocoa,Adlai-Holler/ReactiveCocoa,CCOOOOLL/ReactiveCocoa,bscarano/ReactiveCocoa,yonekawa/ReactiveCocoa,clg0118/ReactiveCocoa,yytong/ReactiveCocoa,rpowelll/ReactiveCocoa,brasbug/ReactiveCocoa,zxq3220122/ReactiveCocoa,xiaobing2007/ReactiveCocoa,gengjf/ReactiveCocoa,zzqiltw/ReactiveCocoa,Liquidsoul/ReactiveCocoa,loupman/ReactiveCocoa,200895045/ReactiveCocoa,shaohung001/ReactiveCocoa,zhaoguohui/ReactiveCocoa,gabemdev/ReactiveCocoa,windgo/ReactiveCocoa,almassapargali/ReactiveCocoa,hoanganh6491/ReactiveCocoa,howandhao/ReactiveCocoa,takeshineshiro/ReactiveCocoa,AndyZhaoHe/ReactiveCocoa,valleyman86/ReactiveCocoa,kiurentu/ReactiveCocoa,emodeqidao/ReactiveCocoa,mtxs007/ReactiveCocoa,hoanganh6491/ReactiveCocoa,FelixYin66/ReactiveCocoa,stupidfive/ReactiveCocoa,hbucius/ReactiveCocoa,SanChain/ReactiveCocoa,libiao88/ReactiveCocoa,nickcheng/ReactiveCocoa,jrmiddle/ReactiveCocoa,rpowelll/ReactiveCocoa,victorlin/ReactiveCocoa,tipbit/ReactiveCocoa,chao95957/ReactiveCocoa,zzzworm/ReactiveCocoa,yaoxiaoyong/ReactiveCocoa,Carthage/ReactiveCocoa,towik/ReactiveCocoa,kiurentu/ReactiveCocoa,qq644531343/ReactiveCocoa,xulibao/ReactiveCocoa,imkerberos/ReactiveCocoa,zhenlove/ReactiveCocoa,ddc391565320/ReactiveCocoa,pzw224/ReactiveCocoa,jam891/ReactiveCocoa,windgo/ReactiveCocoa,KuPai32G/ReactiveCocoa,tzongw/ReactiveCocoa,ohwutup/ReactiveCocoa,clg0118/ReactiveCocoa,Pikdays/ReactiveCocoa,loupman/ReactiveCocoa,clg0118/ReactiveCocoa,SmartEncounter/ReactiveCocoa,itschaitanya/ReactiveCocoa,leelili/ReactiveCocoa,juliangrosshauser/ReactiveCocoa,ericzhou2008/ReactiveCocoa,xulibao/ReactiveCocoa,335g/ReactiveCocoa,LHDsimon/ReactiveCocoa,cstars135/ReactiveCocoa,cstars135/ReactiveCocoa,buildo/ReactiveCocoa,j364960953/ReactiveCocoa,j364960953/ReactiveCocoa,terry408911/ReactiveCocoa,Ethan89/ReactiveCocoa,Farteen/ReactiveCocoa,jianwoo/ReactiveCocoa,xumaolin/ReactiveCocoa,zxq3220122/ReactiveCocoa,JohnJin007/ReactiveCocoa,imkerberos/ReactiveCocoa,monkeydbobo/ReactiveCocoa,Juraldinio/ReactiveCocoa,stevielu/ReactiveCocoa,longv2go/ReactiveCocoa,richeterre/ReactiveCocoa,OneSmallTree/ReactiveCocoa,nikita-leonov/ReactiveCocoa,gengjf/ReactiveCocoa,jaylib/ReactiveCocoa,bensonday/ReactiveCocoa,koamac/ReactiveCocoa,alvinvarghese/ReactiveCocoa,dullgrass/ReactiveCocoa,jackywpy/ReactiveCocoa,stevielu/ReactiveCocoa,DreamHill/ReactiveCocoa,jrmiddle/ReactiveCocoa,sandyway/ReactiveCocoa,BlessNeo/ReactiveCocoa,smilypeda/ReactiveCocoa,Remitly/ReactiveCocoa,lixar/ReactiveCocoa,CQXfly/ReactiveCocoa,kevin-zqw/ReactiveCocoa,tornade0913/ReactiveCocoa,almassapargali/ReactiveCocoa,richeterre/ReactiveCocoa,towik/ReactiveCocoa,hj3938/ReactiveCocoa,jackywpy/ReactiveCocoa,xiaobing2007/ReactiveCocoa,isghe/ReactiveCocoa,hilllinux/ReactiveCocoa,add715/ReactiveCocoa,leichunfeng/ReactiveCocoa,ohwutup/ReactiveCocoa,zhigang1992/ReactiveCocoa,jeelun/ReactiveCocoa,ioshger0125/ReactiveCocoa,esttorhe/ReactiveCocoa,nikita-leonov/ReactiveCocoa,cogddo/ReactiveCocoa,chieryw/ReactiveCocoa,sugar2010/ReactiveCocoa,sandyway/ReactiveCocoa,victorlin/ReactiveCocoa,ericzhou2008/ReactiveCocoa,vincentiss/ReactiveCocoa,tiger8888/ReactiveCocoa,ioshger0125/ReactiveCocoa,sujeking/ReactiveCocoa,PSPDFKit-labs/ReactiveCocoa,PSPDFKit-labs/ReactiveCocoa,swizzlr/ReactiveCocoa,jrmiddle/ReactiveCocoa,jsslai/ReactiveCocoa,itschaitanya/ReactiveCocoa,yangshengchaoios/ReactiveCocoa,shaohung001/ReactiveCocoa,SuPair/ReactiveCocoa,tonyarnold/ReactiveCocoa,bscarano/ReactiveCocoa,taylormoonxu/ReactiveCocoa,add715/ReactiveCocoa,vincentiss/ReactiveCocoa,icepy/ReactiveCocoa,KJin99/ReactiveCocoa,mattpetters/ReactiveCocoa,DongDongDongDong/ReactiveCocoa,luerhouhou/ReactiveCocoa,jeelun/ReactiveCocoa,yizzuide/ReactiveCocoa,PSPDFKit-labs/ReactiveCocoa,Adlai-Holler/ReactiveCocoa,RuiAAPeres/ReactiveCocoa,add715/ReactiveCocoa,tipbit/ReactiveCocoa,takeshineshiro/ReactiveCocoa,DongDongDongDong/ReactiveCocoa,yaoxiaoyong/ReactiveCocoa,esttorhe/ReactiveCocoa,shaohung001/ReactiveCocoa,zhaoguohui/ReactiveCocoa,isghe/ReactiveCocoa,Pingco/ReactiveCocoa,juliangrosshauser/ReactiveCocoa,luerhouhou/ReactiveCocoa,emodeqidao/ReactiveCocoa,KuPai32G/ReactiveCocoa,AlanJN/ReactiveCocoa,ReactiveCocoa/ReactiveSwift,WEIBP/ReactiveCocoa,kaylio/ReactiveCocoa,GuitarPlayer-Ma/ReactiveCocoa,hilllinux/ReactiveCocoa,AndyZhaoHe/ReactiveCocoa,dskatz22/ReactiveCocoa,xiaoliyang/ReactiveCocoa,andersio/ReactiveCocoa,shuxiashusheng/ReactiveCocoa,sugar2010/ReactiveCocoa,itschaitanya/ReactiveCocoa,eliperkins/ReactiveCocoa,yoichitgy/ReactiveCocoa,GuitarPlayer-Ma/ReactiveCocoa,mxxiv/ReactiveCocoa,qq644531343/ReactiveCocoa,zzzworm/ReactiveCocoa,andersio/ReactiveCocoa,xiaoliyang/ReactiveCocoa,ddc391565320/ReactiveCocoa,Khan/ReactiveCocoa,vincentiss/ReactiveCocoa,Rupert-RR/ReactiveCocoa,tonyarnold/ReactiveCocoa,ReactiveCocoa/ReactiveSwift,libiao88/ReactiveCocoa,ikesyo/ReactiveCocoa,tiger8888/ReactiveCocoa,paulyoung/ReactiveCocoa,wangqi211/ReactiveCocoa,BlessNeo/ReactiveCocoa,beni55/ReactiveCocoa,andersio/ReactiveCocoa,200895045/ReactiveCocoa,pzw224/ReactiveCocoa,yangyangluoluo/ReactiveCocoa