bug#70077: An easier way to track buffer changes

[Stefan Monnier]

>> `track-changes-fetch` will call its function argument only once.
>> If several changes happened since last time, `track-changes.el` will
>> summarize them into a single (BEG END BEFORE).
>
> Then I don't think you will be able to guarantee that in all cases.
> You are basically trying to solve a problem that many packages which
> used the modification hooks tried to solve, but where they relied on
> some specifics of the problem they wanted to solve, you are trying to
> solve it in general, and I just don't believe it's possible (but will
> be happy to learn I'm mistaken).

Indeed, there are cases where bugs in our C code will get in the way,
and I'll have to return something like (BEG END :error).
But other than that, the current code already handles
"arbitrary" merging.


        Stefan