Unfortunately, there seems to be a difference in how the `hello_world` example processes rate and volume changes. I'm not sure if it doesn't adjust rate for samples while speaking. In any case, arguably there are just going to be differences in platforms that I can't account for, so this may just have to be. Hopefully it doesn't interfere with actual usage.
* Fix broken delegate method signature.
* Add `NSRunLoop` into `hello_world` example so delegates are called. Presumably, MacOS apps already run one of these, but the example didn't.
* Add necessary dependencies, build script, and `NSSpeechSynthesizer` backend.
* Get very basic speech working.
Needs a delegate to handle queued speech, and currently segfaults if one is set.
`MediaPlayer` only seems to have states for playing and paused, but not stopped. Further, playing when the queue is finished seems to restart playback from the beginning.
Here we clear the list of items to play if the player is paused and we're on the last item. We assume we're done with all items to speak, and clear the list before appending a new item and beginning playback again.
The correct solution is probably to investigate how events work in winrt-rs, but callbacks and Rust have always been a disaster when I've tried them, so I'm hesitant. This does seem to handle the basic scenarios I've thrown at it.
* Move autogenerated code to subcrate to speed up compilation.
* `is_speaking` also checks whether a source is opening, in addition to whether it is playing.
* Return to using autoplay.
Two Tolk instances were being created. One checked for the presence of a screen reader. The other actually performed the speech, and was returned as part of the `TTS` instance.
Unfortunately, Tolk doesn't seem to appreciate being called twice. So here we check if a screen reader is detected and, if one is, return the instance that did the detection. Otherwise, error out and return the WinRT backend.
