Updated readdir example.
  Added sample for showing how to center a window.

  This is just a demo, but will center all GNOME Terminal
 windows - perhaps not waht you want if you have multiple
 ones open, as they'll be on top of each other!
  Ignore object files.
  Added primitive: is_focussed.
Correctly set a timestamp to the libwnck functions.

Some of the libwnck methods require a timestamp to specify when
an event was emitted.  Now we set on.