is deterministic, etc.

In the process of moving to lal/lan, we now have algorithms that used to require a free labelset that no longer do. So for instance, is_deterministic used to refuse to work on lan, which was a problem btw when this lan automaton was proper. But now we have the converse issue: is_deterministic returns true on automaton which is deterministic if \e is viewed as a letter.

This is not acceptable. OpenFST does have this behaviour, but it would be a real nuisance when Vcsn is used for teaching: if you are not proper, you cannot be deterministic.

So we need an intermediate property, and make sure is-deterministic answers properly.

This applies to other properties. See in particular what automaton.info returns.