Jonathan Mercer

Add a super basic implementation of Combine and SwiftUI sample project

2

* adds a combine wrapper to `SAPlayer.Update` * use the wrapper in a SwiftUI friendly way 

## Repro 1. Download a podcast 2. Play for 1 second 3. Put reverb to 20% of the UI 4. Crash ``` 2021-04-21 21:32:19.900136-0700 SwiftAudioPlayer_Example[6063:56482] screen parameters are unexpected: MGScreenClass1125x2436x3x495...