[Gecode] Indexed dependencies for Sets

[Christian Schulte]

Dear all,

I just made the experiments with sets for the new indexed representation.
Unfortunately, it does not buy anything but yields most often a slight slow
down (2%). Only for one example (steiner) one sees a ten percent speedup.

Anyway, as said this is something that had to be done anyway. I will make
the indexed representation the default and remove the old flat
representation. I'll do that in two steps:
 - Remove the old.
 - Remove the class Dependency (not longer needed). That means that
subscribe will take a propagator and a propagation condition. Release does
the same even though I will rename it to cancel (to make it better fit the
picture of a subscription).

Cheers
Christian

--
Christian Schulte, http://www.imit.kth.se/~schulte/