Use interfaces and unsealed attributes for front end apis

[Shadowblitz16]

I would like to write a front end api over arch for my engine.

I need a few things first though.

Can you unseal your generator attributes and make them work with inherited attributes?

I also need a way to wrap your structs, can you convert things like Entity and World to use interfaces like IEntity and IWorld and allow us to write custom implementation of them?

I only need to wrap them, but it could be useful for others to be able to define additional implementation.