InlineEdit: Use Edit Message button for change edit workflow

Allow creating a change edit by changing the commit message with the
existing Edit message button. This way we still support the old
workflow, but we need one more click:

Old workflow:

* Click "Edit Message"
* Edit the message
* Click Save

Now it's one more click:

* Click "Publish Edit"

Change-Id: Ibe86995edde78097f10757e76b427818a1a30007
Deprecate changing message endpoint in non change edit context

Change-Id: Ia1aca9f33d5a31a109df33756ae5d46800792b82
Suppress warning about unused parameter in onEditMessage method

The idx parameter is not used for commit message edits.

Change-Id: I981d757114995b3c679faecd35f66175fc8a142b
Tidy up the 2.11 release notes and add to the index

- Add warning about update via 2.1.7

- Reword paragraph about inline editing

- Reword and fix formatting of 'Generate HTTP Password' removal
paragraph.

Change-Id: I2cd27c573c090526a8ece21232926c0bbd1fc42e