tools.scaffold: more use of hash-sets.
tools.scaffold: more use of hash-sets.

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