Delete old revisions but keep last x versions

Motivation

I wanted to queue revisions that are older than 6 months but keep the last 10 revisions, for example.

This allows me to keep the last 10 revisions and if the 11th is older than 6 months it would be deleted.

The way it is done now as I see it is that we can only pick one or the other.

User interface changes

Will need some changes on the config form.