Move weston-launch to backends/

It's about display servers, not Wayland integration.
main: Refactor some code slightly
Move meta_clutter_init into a new file

We'll use this to get the initialization between the Wayland and
X11 compositor codepaths back in sync.
meta-wayland: Use meta_clutter_init
Move MetaLauncher to meta-backend
Rename the DBus interface files
Remove "xrandr" from the name of the generated DBus files

It's about generic display config, not XRandR specifically.
Rename meta-xrandr-shared to meta-display-config-shared
Start creating different subdirectories for each backend
configure: Add on subdir-objects

To stop automake from complaining
Update .gitignore

It seems the new automake likes to litter these files all around.
configure: Clean up old status line

While I'm here, I might as well. We rely on Xcursor now.