WIP: Dylanmccall/meson build
This branch replaces the old Autotools build system with Meson, adds a Flatpak manifest, and replaces a bunch of X11-dependent code. The downside here is a stronger dependency on Mutter, but that is less of an issue nowadays.
There is still some work to be done adjusting the application to work properly as a Flatpak. In particular, I need to change the helper and settings code to add an autorun file at runtime, and to build as a single executable (with a single name on dbus, probably removing a bunch of unnecessary duplication). That should be in good shape when this branch is ready to merge.
Will probably resolve issue #1.