Remove the xrandr extension

This can't work without a significant rework (because we can't
use GnomeRR in the mutter process, now that's DBus API implemented
by mutter itself, and the monitor config API is private to mutter
for now), and I doubt it's really useful to anyone.
Also, we have an orientation lock button, which kind of serves
a similar purpose
Update all extensions for gnome-shell 3.9.90

addActor() gone from PopupBaseMenuItem, arrows in menus,
SystemStatusButton gone.
The auto-move-windows cleanup is probably older, weird noone
noticed before.

Anyway, I need a pitch fork.