This allows negative numbers, which also means functions which took numbers can now take negative numbers
Luckily, they all already handled this exactly as expected.
I've extracted the `builtin_log_root` template for users to customize the
default templates without fully overriding them, for example I would remove
the change_id/commit_id for myself - and we discussed in Discord that leaving
those makes sense for the user to be reminded/teached that the root commit has
a change id made from z's.
