ODM: Consider derived object classes as well

[kwin]

Currently for mapping LDAP entries to ODM annotated classes the objectclass field on the annotation @Entry is evaluated. The mapping considers only LDAP entries having the given class explicitly set as eligible for mapping. In some cases that objectclass is not explicitly set, but rather a more specific objectclass, which derives from the required objectclass (e.g. inetOrgPerson instead of Person). Of course those entries should also be considered when doing the mapping.

Not sure how to implement that, because to consider any derived objectclasses one would probably need to retrieve the according schema (even transitively).

[kwin]

Probably subschemaSubentry can be used to retrieve the hierarchy: https://tools.ietf.org/html/rfc4512#section-4.2

[kwin]

This seems to duplicate #338.