This makes it easier to spot syntax errors when editing the
class reference. The schema is referenced locally so validation
can still work offline.
Each class XML's schema conformance is also checked on GitHub Actions.
* Renames for 2D and 3D
* Class name was confusing, given both 2D and 3D have a "visible" property that is unrelated to actual on-screen visibility.
* New name makes it clear that this is about visibility on screen.
