transplant: replace incancestors uses with ancestors

revlog.ancestors: add support for including revs This is in preparation for an upcoming refactoring. This also fixes a bug in incancestors, where if an element of revs was an ancestor of another it would be generated twice.

perf: add command to test performance of membership in ancestor set The new command, perfancestorset, takes an argument denoting which revset to test the membership of. Currently this runs through all the ancestors and converts them into a set. The primary purpose of having this is to compare this approach, currently used in several places, against the upcoming lazy approach.