This resolves the previously-noticed bindgen issue, where gdnative and speech-dispatcher require conflicting versions.
The early iOS build failures appear due to attempting to link AppKit on iOS, where it doesn't exist. This seemed to work on Rust 1.45, but now fails on 1.46.
Hopefully, this plus tts-rs changes get this building under iOS again.
* Add ability to detect when speaking. Doesn't yet work under Linux or WinRT.
* Add signal to indicate when speaking is done.
* Refine screen reader detection under Android.
* Initial WinRT driver, used when no Windows screen reader is detected.
* Enhanced rate support, tracking min/max/normal rate per synthesizer.
* `rate_percentage` properties make working with differing rate ranges easier.
