annotate: simplify annotate parent function The annotate algorithm used a custom parents() function to try to reuse filectx and filelogs. I simplified it a bit to rely more heavily on the self.parents() which makes it work well with alternative filectx implementations. I tested performance on a file with 5000+ revisions but no renames, and on a file with 500 revisions repeating a series of 4 edits+renames and saw zero performance hit. In fact, it was reliably a couple milliseconds faster now. Added the perfannotate command to contrib/perf.py for future use.

changegroup: move changegroup file adding to a separate function Moving the logic that adds files to a changegroup to a different function allows extensions to override it and customize the way filelogs are added to changegroups. No logic is changed.

log: move log file walk to its own function This moves the logic that determines which changesets to process during a 'hg log foo.txt' command. Putting it in its own function allows extensions to modify how the file log is traversed. For instance, the current implementation uses filelog revs heavily. Other implementations may not have filelog revs available. The function throws an exception if the traversal is not possible via the filelog, so the parent function can do things the slow way if necessary (by walking the entire commit history). Aside from the exception throwing, no logic is changed.