calendar: Rename internal word, add days-until
calendar: Rename internal word, add days-until

Fixes #752

factor/factor,tgunr/factor,factor/factor,factor/factor,tgunr/factor,tgunr/factor,tgunr/factor,factor/factor,tgunr/factor,mrjbq7/factor,mrjbq7/factor,mrjbq7/factor,mrjbq7/factor,tgunr/factor,mrjbq7/factor,mrjbq7/factor,factor/factor,factor/factor