Implement most Signal operators as protocol extensions
Implement most Signal operators as protocol extensions

This implements all but a couple Signal operators as protocol extension
methods. The remaining ones I've yet to figure out a way to implement
that doesn't crash the swift compiler. For now the free-functions have
been left but now forward to the protocol methdods.

yonekawa/ReactiveCocoa,andersio/ReactiveCocoa,Juraldinio/ReactiveCocoa,ReactiveCocoa/ReactiveSwift,PSPDFKit-labs/ReactiveCocoa,RuiAAPeres/ReactiveCocoa,calebd/ReactiveCocoa,walkingsmarts/ReactiveCocoa,andersio/ReactiveCocoa,kevin-zqw/ReactiveCocoa,tzongw/ReactiveCocoa,esttorhe/ReactiveCocoa,llb1119/test,ikesyo/ReactiveCocoa,beni55/ReactiveCocoa,kevin-zqw/ReactiveCocoa,ikesyo/ReactiveCocoa,paulyoung/ReactiveCocoa,Farteen/ReactiveCocoa,esttorhe/ReactiveCocoa,esttorhe/ReactiveCocoa,smilypeda/ReactiveCocoa,Juraldinio/ReactiveCocoa,paulyoung/ReactiveCocoa,calebd/ReactiveCocoa,paulyoung/ReactiveCocoa,PSPDFKit-labs/ReactiveCocoa,calebd/ReactiveCocoa,ohwutup/ReactiveCocoa,sandyway/ReactiveCocoa,ohwutup/ReactiveCocoa,PSPDFKit-labs/ReactiveCocoa,llb1119/test,natestedman/ReactiveCocoa,tonyarnold/ReactiveCocoa,sandyway/ReactiveCocoa,walkingsmarts/ReactiveCocoa,yonekawa/ReactiveCocoa,smilypeda/ReactiveCocoa,Juraldinio/ReactiveCocoa,rpowelll/ReactiveCocoa,beni55/ReactiveCocoa,tzongw/ReactiveCocoa,tonyarnold/ReactiveCocoa,tonyarnold/ReactiveCocoa,ohwutup/ReactiveCocoa,llb1119/test,Farteen/ReactiveCocoa,victorlin/ReactiveCocoa,RuiAAPeres/ReactiveCocoa,victorlin/ReactiveCocoa,kevin-zqw/ReactiveCocoa,rpowelll/ReactiveCocoa,victorlin/ReactiveCocoa,natestedman/ReactiveCocoa,sandyway/ReactiveCocoa,yonekawa/ReactiveCocoa,ReactiveCocoa/ReactiveSwift,esttorhe/ReactiveCocoa,ReactiveCocoa/ReactiveSwift,natestedman/ReactiveCocoa,rpowelll/ReactiveCocoa,Farteen/ReactiveCocoa,beni55/ReactiveCocoa,walkingsmarts/ReactiveCocoa,RuiAAPeres/ReactiveCocoa,smilypeda/ReactiveCocoa,andersio/ReactiveCocoa,tzongw/ReactiveCocoa