Port the xdg_shell implementation to use the unstable v6 protocol. This
includes:
- making xdg_surface a generic base interface for xdg_shell surface
roles
- create a xdg_toplevel role replacing the old xdg_surface
- change the xdg_opup role to be based on xdg_surface
- make xdg_popup not grab by default
- add support for xdg_positioner
https://bugzilla.gnome.org/show_bug.cgi?id=769936
Move xdg_shell related functionality to a new meta-wayland-xdg-shell.c
and wl_shell related functionality to a new meta-wayland-wl-shell.c,
and adapt role object tree.
Common functionality related to the surface being drawn as a
MetaSurfaceActor was moved to a MetaWaylandSurfaceRoleActorSurface role.
The subsurface role GObject is made to inherit the actor surface GObject.
Shell surface hooks (configure, ping, close, popup done) were added to
a MetaWaylandSurfaceRoleShellSurface GObject which inherits the
surface actor role GObject.
The shell surface roles (xdg_surface, xdg_popup, wl_shell_surface) are
made to inherit the shell surface GObject and implement the relevant
API.
https://bugzilla.gnome.org/show_bug.cgi?id=757623https://bugzilla.gnome.org/show_bug.cgi?id=763431
