Compress events as part of the frame cycle

Compress events as part of the frame cycle

Instead of trying to guess about which motion events are
extraneous, queue up all events until we process a frame.
This allows us to look ahead and reliably compress consecutive
sequence of motion events.

clutter-main.c: Feed received events to the stage for queueing.
  Remove old compression code. Remove clutter_get_motion_events_frequency()
  clutter_set_motion_events_frequency()
clutter-stage.c: Keep a queue of pending events.
clutter-master-clock.c: Add processng of queued events to the
  clock source dispatch function.

http://bugzilla.openedhand.com/show_bug.cgi?id=1637

Signed-off-by: Emmanuele Bassi <ebassi@linux.intel.com>