Update BREAKING.md formatting
+ Change Mutex, Sem, Cond to have methods instead of functions
+ Merge `KeyUpEvent` and `KeyDownEvent` into `KeyboardEvent`
+ Haptic functions now return bool and/or error instead of int
-+ Change GameControllerMapping() into GameController.Mapping()
++ Change `GameControllerMapping()` into `GameController.Mapping()`
- Unexported `Padding` in `AudioSpec` struct
- Unexported `goHintCallback`
