add checks to fill_dir that prevent filling anything that's already up to date

[juniperlsimonis]

as of now, fill_dir basically fills everything, even if it already exists. this slows stuff down when you just want to "check if your data are up to date, and update them if not".

[juniperlsimonis]

it's actually parsed out well now and the slow things that make this obnoxious can be turned off easily or not done,