revset: use _generatorset directly in _revdescendant _ascgeneratorset is going away.

generatorset: move membership testing on ordered gen to the main class We are phasing out the ordered version of the class to simplify the code.

generatorset: make use of the new mechanism in the subclass Until we remove them, we use the new parameter of _generatorset to make sure the code is run.

generatorset: make it possible to use gen as fastasc or fastdesc We gain a parameter to inform that the generator is ascending or descending. If the generator is ordered, it is also used for the `fastasc` or `fastdesc` version. The _ascgeneratorset and _descgeneratorset class will be removed soon.

baseset: rely on the abstractsmartset implementation for filter

_orderedsetmixin: drop this now unused class All my friends are dead.

spanset: drop _orderedsetmixin inheritance The min/max method are as well provided by abstractsmartset.

orderedlazyset: drop this now unused class All my friends are dead.

_descendant: use filteredset instead of orderedlazyset The orderedlazyset class is going away. Filteredset gives the same service.

addset: use the base implementation for ascending and descending

addset: use base implementation for __filter__

addset: use base implementation for __add__

addset: use base implementation for __sub__

addset: use base implementation for __and__

addset: promote to real smartset Better revset performance are also achieved with less overlay. There is no good reason for addset to not be a smartset. We can replace the `_orderedsetmixin` inheritance since `abstractsmartset` has efficient min and max too.

addset: add a __nonzero__ method This is required to be a full smartset (not sure what was happening before that...)

addset: offer a fastasc and fastdesc methods If the underlying object offers fast iterators, we use them to provide fast iterators too.

addset: split simple and ordered iteration We have two goals here. First, we would like to restore the former iteration order we had in 2.9. Second, we want this logic to be reusable for `fastasc` and `fastdesc` methods.

generatorset: promote to smartset This is not going to be efficient but we need all basic set classes to be smartsets for the other classes to work.

generatorset: implement __nonzero__ This is necessary to become a real smartset.

spanset: use base implementation for __add__

spanset: use base implementation for __sub__

spanset: use base implementation for __and__

spanset: use base implementation for filter