setSpeechEngineReadyCallback

Sets a callback which returns the speech engine ready status. Set the speech engine activity status using this lambda to avoid speech event conflicts. This logic is used by RouteTracker before new RouteTracker.newVoiceGuidance is raised to check if the speech engine is busy. If it is busy it will postpone raising the voice guidance event until next RouteTracker.trackLocation will be called. Here is an example of how it can be used with a text-to-speech engine:

routeTracker.setSpeechEngineReadyCallback {
 !TextToSpeech.isSpeaking
}