#todo
- add crate that simplifies plugins
- add tweening
- port utils from rusty cauldron (anim, mouse, save, tools, tween)
- tidy up folder hierarchy
- port utils from not quite tennis? (audio maybe?)
- add leafwing input
- add time crate
- game pause
- splash screen
- reset state
- screen shake
- opacity propagation?
- fade state transition