create download directory if absent
protect % within filenames

also color all filenames yellow
allow date/time placeholders in download directory

strftime(3) format is used, so you could try "/some/dir/%Y-%m-%d"
this fixes issue #1

note: ~ is not expanded to $HOME (yet)
refactor: use fixed instead of interpolated strings where possible
update 4chan link format

hopefully the old one is not used any more, removed it