Customizable Player Models

Updated Simplified Chinese translation (#333)

Fixed crash with optifabric on 1.19
Fixed skulls not rendering with Optifine on 1.18+
Fixed button order spinner not showing the correct value
Fixed mouse errors in the animation editor when no animation is selected
Fixed gizmo rendering multiple times in the animation editor
Fixed model not rendering in the editor after test-in-game (Closes #335)
Fixed pre 1.8 skin converter not working in some cases