NE_GT Classes - Houses all non-interface classes that should exist in an ne_gt environment. These classes simply define generic types. They should not have anything to do with relationships between specific types in a virtual world. For example, a Domain and a User exist in this repo, but the Relationship between a User and another User, or the fact that a User within a Domain is a DomainMember should not. These in particular belong in the ne_gw repo.