revset: added sort method in addset We need this method to duck-type generatorset since this class is not going to be used outside revset.py and we don't need to duck-type baseset. This sort method will only do something when the addset is not already sorted or is not sorted in the way we want it to be.

revset: added reverse method to addset This method is needed to duck type generatorset.

revset: changed _iterator() method on addset to work with a given order If the two collections are in ascending order, yield their values in an ordered way by iterating both at the same time and picking the values to yield.

revset: changed _iterator() in addset to use the generated list when available Now when all the elements have been generated, the iterator will just use the generated list instead of going through all the elements again.