"flash" does not work in teardown_request!

Instead, logging the messages to the app logger.
It does not make sens to pass a default ID here.

It's the primary key. It does not make sens to create multiple instances with
the same key. Also, it's quite unlikely that the case of the default key
arrives often enough to warrant the default behaviour.
Properly setting the form ID.

It's no longer an auto-increment!