fix hgrc doc hook descriptions.

hooks: distinguish between locally committed and incoming changes. "commit" hook is now for locally committed changes only. "incoming" is for changes pulled, pushed, or unbundled into local repo.

Allow callers to pass in the dirstate lock in most localrepo.py funcs. This makes it possible to take the lock once and commit a large number of patches, without having to read and write the dirstate for each patch.