Per Manuel Arostegui in T263817#7033384. The limit is 5000.
(I picked it arbitrarily, there's no real rationale for it.)
Also log a warning when any user reaches half of the limit,
so that we might make a decision about changing this mechanism
before it starts affecting users. Maybe at that time we'll
have data to show that it's safe to remove the limit.
Bug: T263817
Change-Id: I18a8ee0ad7383759229c5721d5253fb591457d4d
The existing comment IDs can't be used to find the same comment on
a different revision or page (when it's transcluded), because they
depend on the comment's parent and its position on the page.
Comment names depend only on the author and timestamp. The trade-off
is that they can't distinguish comments posted within the same minute,
or in the same edit, so we will still need the IDs sometimes.
Prefer using comment names when replying, if they're not ambiguous.
This fixes T273413 and T275821.
Heading names depend on the author and timestamp of the oldest comment.
This way we don't have to detect changes to the heading text, but we
can't distinguish headings without any comments.
Bug: T274685
Bug: T273413
Bug: T275821
Change-Id: Id85c50ba38d1e532cec106708c077b908a3fcd49