metamodel #226: added Model.container

it's redundant with Member.declaringClassOrInterface though, but not sure how to unify the two
at least that one works even when you have bound attributes -> value which are not members anymore
metamodel #226: implemented `string` for every metamodel
metamodel: fixed a bogus @TypeInfo
metamodel tests #226: removed a few prints
metamodel tests #226: test `string` on metamodel