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.
For the time being we don't support writing a description for those, preferring
having all details in the method's description.
Using self-closing tags saves half the lines, and prevents contributors from
thinking that they should write the argument or return documentation there.
- Move most properties from TileMap to TileSet,
- Make TileSet more flexible, supporting more feature (several
collision layers, etc...),
- Fusion both the TileMap and TileSet editor,
- Implement TileSetSources, and thus a new way to index tiles in the TileSet,
- Rework the TileSet and TileMap editors completely,
- Implement an editor zoom widget (and use it in several places)
