The current handling of settings is a very roundabout leftover from the days of
gconf. Simplify and handle the setting more directly. At the same time move
handling of saving the window state to gsettings instead of saving it to a
config file.
taken from:
https://github.com/mate-desktop/eom/commit/a2055e1
- bumped required intltool version to 0.50.1
- renamed and corrected gschema xml for proper intltool usage
- removed obsolete lines from po/POTFILES.skip
