When adding entries to scenery groups by hand, like we do for a lot of ToonTowner's stuff, it currently tries to get the loaded scenery group. If this happens not to be loaded at that time, this will fail.
Instead, hardcode the headers - that's how object .DATs do this anyway.
* GCC suddenly decided `Object` should be marked as `final`, however it is
used as a base class for more specific types that inherit from it.
* Also ignore -Wsuggest-final-methods for Object class
* Guard Object::GetName from being final