help: drop -a from heads syntax summary (issue3483)

revlog: add optional stoprev arg to revlog.ancestors() This will be used as a step in removing reachable() in a future diff. Doing it now because bryano is in the process of rewriting ancestors in C. This depends on bryano's patch to replace *revs with revs in the declaration of revlog.ancestors.

revlog: descendants(*revs) becomes descendants(revs) (API) Once again making the API more rational, as with ancestors.

revlog: ancestors(*revs) becomes ancestors(revs) (API) Accepting a variable number of arguments as the old API did is deeply ugly, particularly as it means the API can't be extended with new arguments. Partly as a result, we have at least three different implementations of the same ancestors algorithm (!?). Most callers were forced to call ancestors(*somelist), adding to both inefficiency and ugliness.

config: make sortdict keys() and iterkeys() methods respect the item order The config.sortdict class is a simple "sorted dictionary" container class, based on python's regular dict container. The main difference compared to regular dicts is that sortdicts remember the order in which items have been added to it. Without this patch the items() method returns the sortdict elements in the right order. However, getting the list of keys by using the keys() or iterkeys() methods, and consequencly, looping through the container elements in a for loop does not respect that order. This patch fixes this problem.

merge with stable

parsers: replace magic number 64 with symbolic constant

revset: introduce and use _revsbetween This is similar in spirit to revlog.nodesbetween, but less ambitious, much simpler, and ~2x faster.

revset: implement dagrange directly This is much faster than the older implementation (~8x).

revset: turn dagrange into a function