Changing default fillfactor for the whole database

Hi there,

I have a scenario where virtually all user tables in the database will need to
have a lower fill factor.

It would have been handy to have a way to set this default, but as of now, I
don't think the default can be changed.

I have looked at `share/postgresql.conf.sample` file, and couldn't see
anything indicating this value could be changed.

Though I'm aware there's an ALTER TABLE command that can be used for that, I
think it would be good to avoid some future errors (forgetting to set it) if I
could change the default value.

Does this make sense? Have I missed something about being able to change this
on a database level?

Thanks,
Marcelo.