evolve: extend obsstore object to use prune parent information Now that we have the information, we can use it to build a mapping to access all marker that prune a children of a node. This is similar to what we do for successors and precursors. The performance impact is a few tens of second on my mercurial clone. Experimenting is worth the trouble.

prune: wrap mercurial internal to add parent information in prune marker We store as a p1 (and p2) key in the extra dict for marker. This allow us to record this information for future use without requiering a format change.

evolve: drop `latercomer` and `conflicting` compatibility. Those old alias are deprecated for a long time now. All computations related to troubles are in Mercurial core for multiple versions.