TODO

caching of thumbnails doesn't seem to take thumbnail size into account.
Change sizes and you get the old thumbs....

Option --autograb for feh to grab keyboard - so you can control feh without
having to focus it. Have to be a bit careful with this but could be useful.

Now we have 10 --action* options, would be nice to hit a key and get a text
overlay reminder showing what each one does :p

key/option/signal/timeout to totally reload filelist (rescan directories etc)