bug#16301: 24.3.50; [Feature] Split add-change-log-entry to make it reusable

[Noam Postavsky]

Daniel Dehennin <daniel.dehennin@baby-gnu.org> writes:

> I just start to use magit in complement[1] of vc-git and was wondering
> why there is no feature like “add-change-log-entry(-other-window)” that
> insert in the commit log instead of creating/adding to a plain
> ChangeLog.
>
> I finally found[2] the “magit-commit-add-log” which behave like what I
> had in DVC[3].
>
> All these functions do near the same thing but code is duplicated.
>
> I propose to split the “add-change-log-entry” function to make parts
> usable by third parties.

I've started working on this, patch attached below.  It's not entirely
baked, but I thought I'd post it now to let people know about it.

0001-Improved-ChangeLog-generation-for-vc-log-Bug-16301.patch
Description: patch