UI is improperly accessible for screen readers

[Windows-Electronic101]

In multiple cases whenever edit fields exist, screen readers do not read the contents of the edit box. In NVDA's case, it only says blank. Additionally, when selecting voices in the manage models screen, space cannot be used to select checkboxes.

[willwade]

Im really not hugely confident I've done a great job - but it should be a bit better in the https://github.com/AACTools/VoiceGarden-SAPI/releases/tag/v0.5.8 release. Really welcome feedback though

NB: I strongly imagine these voices are not great for ScreenReaders - word event timings for one is waaay all over the shop