add some more utility words like when-empty
add some more utility words like when-empty

sarvex/factor-lang,dch/factor,mrjbq7/factor,littledan/Factor,dharmatech/factor,AlexIljin/factor,nicolas-p/factor,tgunr/factor,factor/factor,mrjbq7/factor,bjourne/factor,seckar/factor,bjourne/factor,nicolas-p/factor,bpollack/factor,mcandre/factor,erg/factor,factor/factor,mrjbq7/factor,slavapestov/factor,bpollack/factor,dch/factor,AlexIljin/factor,AlexIljin/factor,jwmerrill/factor,littledan/Factor,AlexIljin/factor,nicolas-p/factor,littledan/Factor,sarvex/factor-lang,bpollack/factor,AlexIljin/factor,bjourne/factor,ceninan/factor,tgunr/factor,seckar/factor,dharmatech/factor,bpollack/factor,slavapestov/factor,bjourne/factor,mcandre/factor,sarvex/factor-lang,Keyholder/factor,cataska/factor,Keyholder/factor,mcandre/factor,erg/factor,mcandre/factor,kingcons/factor,bpollack/factor,ehird/factor,AlexIljin/factor,sarvex/factor-lang,factor/factor,tgunr/factor,slavapestov/factor,ehird/factor,bjourne/factor,mrjbq7/factor,ceninan/factor,mcandre/factor,nicolas-p/factor,nicolas-p/factor,factor/factor,tgunr/factor,bjourne/factor,dch/factor,sarvex/factor-lang,mrjbq7/factor,AlexIljin/factor,bjourne/factor,kingcons/factor,nicolas-p/factor,erg/factor,mcandre/factor,slavapestov/factor,mcandre/factor,Keyholder/factor,dch/factor,erg/factor,sarvex/factor-lang,sarvex/factor-lang,kingcons/factor,erg/factor,dch/factor,factor/factor,bpollack/factor,seckar/factor,slavapestov/factor,cataska/factor,erg/factor,bpollack/factor,tgunr/factor,jwmerrill/factor,ehird/factor,ceninan/factor,dharmatech/factor,cataska/factor,cataska/factor,ceninan/factor,littledan/Factor,erg/factor,jwmerrill/factor,dch/factor,slavapestov/factor,factor/factor,slavapestov/factor,kingcons/factor,nicolas-p/factor,mrjbq7/factor,tgunr/factor