* Add speech rate setting
* Add volume slider
* New speech manager skeleton
* User API key from resx
* Implement voice list retrieve via new api
* Rewrite to use ObAPI, remove all dependancies
* Use volume setting
* Clean up using statements
* Volume and timing adjustments
* Lookup rate value
* Use numeric rates for tighter spread
* Manage plugin data folder via core interface
* Add check that nullable settings are not null.
* Get file size before it's deleted.
* Improve old settings migration.
* Ignore cache sizes below 1MB
* Re-index orphaned files in cache, purge legacy wav files.
* Call top level error logging for native voice exception.
* Async title and detail requests to remove pause
* Remove NetCoreAudio use of temp files.
* Remove orphan using.
