Added some newlines for xmobar's sake
wallpaper.sh pages through wallpapers by age

Meant to do this for a while but had several false starts and it ended up being trickier than expected.

find is great for matching criteria.  Giving me files newer than a file is great, but they're not ordered.  sort handles ordering, but to get that I have to give find a printf to show the mtime, then sort, then trim the dates.  This is doable, it's just not elegant.  Where this failed is that there is no -older, and -not -newer give sme items with the same age.

ls -t worked better.  I caved and used an array to track position.  Also caved and renamed my three files with spaces in them so they wouldn't have spaces anymore.

Anyway, wallpapers.sh with no args still does a random wall.  `new` will pick one newer than current.  `old` picks the next oldest.

Current wallpaper is tracked by a symlink.  I figure I can target this in .xsession and preserve wallpapers from session to sessoin.

Debating adding newest and old (because really what I want is to load up my shiny new wallpaper I just found) but I'm already running out of modifiers in xmonad.