Code generation messes with the actual source directory and makes it
impossible to use tools like clippy without having generated the config
via meson.
[Fenv](https://gitlab.gnome.org/ZanderBrown/fenv/) makes it easier to
build and run flatpak applications from command line. Its artifacts are
put in a .fenv folder, which should be ignored.
The initial commit of gnome-image-viewer.
Things are in an MVP state, with image viewing and
opening from the desktop functional. We also can
open images externally, print them, and set them as
backgrounds.
