Updated to 1.21.2/1.21.3
Added mod support and polished code.
- Updated to 1.21
- Implemented an easier way of adding screens to apply a button to.
TODO: Implement an api to add your own entries for mod support.
- Ported down to Minecraft versions 1.20 and 1.20.1.
- Modified button widget textures to compensate for the pre 1.20.2 way of making button widgets.
Initial release.
