cubicweb-container #3845605 make it possible to detect etypes that can live without a container [resolved]

(More or less related to my "favorite" issue. This time, the motivation is to ease security setup.)

I suggest to add a "strict" keyword argument to structure configuration method, that would stop processing entity types if the cardinality of a relation does not enforce belonging to the container (i.e. not in '+1').

In addition a method orphan_etypes (could not find a better name) would return those entity types that can live outside a container.

done in2.5.0
load left0.000
closed by#b67e4bcb4ff5 Add a `strict` keyword argument to `structure` configuration method
patchAdd a `orphan_etypes` method to container configuration [rejected]