Add a helper function, that constructs a path to a config file from
XDG_CONFIG_HOME environment variable, by the rules of
http://standards.freedesktop.org/basedir-spec/basedir-spec-latest.html
Make desktop-shell find its config file from XDG_CONFIG_HOME. This
allows to have a personal config file without continuously fighting with
git about wayland-desktop-shell.ini.
Signed-off-by: Pekka Paalanen <ppaalanen@gmail.com>
Pekka Paalanen
Kristian Høgsberg