rusty_audio 1.1.0

# Version 1.1.0
## 10 Oct 2019

- Added the `.wait()` method to `Audio` to block until no sounds are playing.

# Version 1.0.0
## 10 Oct 2019

- Initial release, ported from [rusty_sword_arena](https://github.com/cleancut/rusty_sword_arena)
  so it can be reused in other projects such as 
  [rusty_sword](https://github.com/cleancut/rusty_sword)