Overlay and Genealogy Functionality

[tendai-zw]

This PR adds the following:

1. Method to add Overlays to an Entity
2. Defines fixed Overlay Types and Positions using an Enum to prevent modifications to abuse method
3. Add functionality to parse Genealogy from the request - this is useful when dealing with inherited Entities as the client does not send the input type. This is useful for rare cases where developers want to modify an incoming request and return it back to the Client to merge.
4. Documentation for the above changes
5. Example Transform showing how to use overlays