PostgreSQL 12 support

So much to do, so little time...

While I have a lot of plans what I like to do, I have virtually no time to do so, and for my daily work, it is just "good enough", knowing how to deal with the quirks still not fixed. But having the PostgreSQL 12 release out now, there was no more waiting, so the mod_pg modules was updated and a minor Admin4 update is out now.