Relax the status version check to ignore the third digit.

Changes to the third digit should indicate changes that are both
forwards and backwards compatible.
test-conflicted: use the recommended log message.

Use the recommended log message when committing the manual conflict
resolution, rather than specifying a log message on the command line..
Keep track of the names of the branch tips.

Record the original names of the branch tips.  These will be handy for
generating better commit messages.
reparent(): allow a commit message optionally to be specified.
automerge(): allow a commit message optionally to be specified.
Store the merge name in every Block.

It will be used for constructing log messages.
Block.auto_outline().do_merge(): set meaningful commit messages.

When outlining a block, set meaningful commit messages on the
merge commits that are created.
request_user_merge(): change suggested log message.

Make the log message suggested for manual merges have the same format
as those used for automatic merges.
MergeState.simplify_to_merge(): mention the two tip names in log message.

If an incremental merge is simplified to a merge, then include the
names of the two original tips in the suggested commit message.
Extend log message when simplifying to rebase-with-history.

When simplifying to rebase-with-history, append a note to the log
message explaining where the commit came from.  This is analogous to
the message the can be appended by "git cherry-pick", but in this case
we make it the default because the commit that was rebased will
necessarily remain in the history.
Merge branch 'name-tips'

* Keep track of the names of the tips of the branches being imerged.

* Create better commit messages for the micromerges.

* When simplifying to merge, name the original branch tips in the
  suggested commit message.

* When simplifying to rebase-with-history, append a note to the commit
  message describing what happened.