Refactoring: renamed IEntity2 to IRuntimeEntity.
Refactoring: moved IRuntimeEntity and ProxyBasedRuntimeEntity to Starcounter.Advanced (catalog and namespace).
Introduced new class EntityBasedRuntimeEntity that can expose any Entity-based class as a IRuntimeEntity and changed Entity so that it does not implement IRuntimeInterface, but instead use the dedicated class.
Removed Entity.From method in favor of new EntityHelper.ToEntity method with the same semantics.
Refactoring: moved EntityHelper to Starcounter.Advanced (namespace and folder).