Include user-dirs.dirs in .profile, and use capitalised versions of the set names.

We already use auto-capitalisation in the shell, so we actually benefit
from having capitalised names, considering it reduces headaches induced
by hardcoded paths. Also, now that we've accepted that the home
directory will be a mess, it will aid standing out.

Also source the file in .profile, because it should've been from the
start.

.fehbg

@@ -0,0 +1,2 @@
+#!/bin/sh
+feh --no-fehbg --image-bg black --bg-center "$(xdg-user-dir PICTURES)/eumetsat/curr.png"