Greedy algorithm to the setcover assignment

[BaltiBoix]

Rough and dirty greedy algorithm for the setcover assignment:
1. Order by c = Cost of set/nº of items covered. Removing first the items already covered
2. Add the set with the min c.
3. Repeat until all the items are covered

Iterate randomly changing the order of the sets and distorting the cost randomly between 0.85 and 1.15

Gets 7/10 in the 6 cases.

[ccoffrin]

Sorry for the delay, just getting around to this.

The code looks resonable. For the sake of consistency I suggest we rename the directory to isl_001 short for iterated local search.