prettyprint: fix .b, .o, and .h for negative numbers.
prettyprint: fix .b, .o, and .h for negative numbers.

Also makes these useful for nested printing in different number bases.

AlexIljin/factor,bpollack/factor,AlexIljin/factor,bpollack/factor,factor/factor,AlexIljin/factor,mrjbq7/factor,factor/factor,mrjbq7/factor,tgunr/factor,AlexIljin/factor,bpollack/factor,factor/factor,bpollack/factor,tgunr/factor,factor/factor,tgunr/factor,mrjbq7/factor,tgunr/factor,AlexIljin/factor,mrjbq7/factor,tgunr/factor,bpollack/factor,AlexIljin/factor,factor/factor,bpollack/factor,bpollack/factor,mrjbq7/factor,factor/factor,AlexIljin/factor,tgunr/factor,mrjbq7/factor