Release v0.8.0

• Adds onEnd callback that gets invoked for SpeechSynthesisUtterance.end and HTMLMediaElement.ended events.
• Adds a rate parameter to set the initial SpeechSynthesisUtterance.rate or the HTMLMediaElement.defaultPlaybackRate.
• Adds a volume parameter to set the volume.
• Delegates handling of resume/play to the controller class behind useTts.

The volume and rate are clamped by their respective specs (HTMLMediaElement or SpeechSynthesisUtterance).