bit-sets: some cleanup, small performance improvement to members.
bit-sets: some cleanup, small performance improvement to members.

nicolas-p/factor,mrjbq7/factor,bjourne/factor,nicolas-p/factor,nicolas-p/factor,slavapestov/factor,sarvex/factor-lang,dch/factor,bpollack/factor,sarvex/factor-lang,nicolas-p/factor,bpollack/factor,sarvex/factor-lang,dch/factor,tgunr/factor,mrjbq7/factor,factor/factor,bjourne/factor,AlexIljin/factor,nicolas-p/factor,dch/factor,mrjbq7/factor,factor/factor,bpollack/factor,bpollack/factor,factor/factor,bpollack/factor,tgunr/factor,sarvex/factor-lang,dch/factor,dch/factor,AlexIljin/factor,dch/factor,mrjbq7/factor,tgunr/factor,AlexIljin/factor,bjourne/factor,mrjbq7/factor,sarvex/factor-lang,nicolas-p/factor,factor/factor,bjourne/factor,bjourne/factor,nicolas-p/factor,bjourne/factor,slavapestov/factor,factor/factor,tgunr/factor,AlexIljin/factor,AlexIljin/factor,tgunr/factor,sarvex/factor-lang,sarvex/factor-lang,slavapestov/factor,slavapestov/factor,slavapestov/factor,slavapestov/factor,tgunr/factor,AlexIljin/factor,slavapestov/factor,mrjbq7/factor,factor/factor,bpollack/factor,bjourne/factor,AlexIljin/factor,bpollack/factor