Right now this just has all of the files in one directory. We'll
be introducing more structure to this in the future, and build
a proper backend system.
For whatever reason, this hash table was in the generic
implementation section instead of the XSync implementation,
even though it's only used by the XSync implementation.
Use it as a first pass of things to move over.
To allow other clients (gnome-session, gnome-settings-daemon)
to monitor user activity, introduce a DBus interface for the
idle monitor inside mutter.
https://bugzilla.gnome.org/show_bug.cgi?id=706005
When running as a wayland compositor, we can't use the xserver's
IDLETIME, because that's updated only in response to X events.
But we have all the events ourselves, so we can just run the timer
in process.
https://bugzilla.gnome.org/show_bug.cgi?id=706005