data: put wayland session in its own directory

Right now, display managers look for sessions in /usr/share/xsessions.

We stuff gnome-shell-wayland.desktop there and then that entry shows up
in the display manager session list.  It won't work, since the display
manager doesn't support launching wayland, though.

This commit moves it to /usr/share/wayland-sessions so that display
managers can 'opt in' to showing wayland sessions, once they support
them.

This breaks hardcode freeze.

Approved-By: Matthias Clasen <mclasen@redhat.com>
Approved-By: Javier Jardón <jjardon@gnome.org>
NEWS: update for release
configure: bump to 3.10.0
Updated translation for Afrikaans (af)