Log Message:
Update to 2.19

https://git.finalrewind.org/feh/plain/ChangeLog
Tue, 06 Jun 2017 20:40:00 +0200  Daniel Friesel <derf+feh@finalrewind.org>

* Release v2.19
    * Follow the freedesktop.org Thumbnail Managing Standard by saving
      thumbnails in ${XDG_CACHE_HOME}/thumbnails (defaulting to
      ~/.cache/thumbnails) instead of ~/.thumbnails
      (patch by Olof-Joachim Frahm)
    * Install app icons with the correct permissions of 644
    * Documentation improvements