Type some text and press "Speak" to synthesize and play it.
Streaming playback
play() starts speaking before the whole text is rendered, and keeps one
chunk of lookahead. "Cut and start the next line" interrupts an utterance while that
lookahead is still being rendered, then immediately asks for a different one — the
sequence that used to wedge the engine
(#67). Watch the log: the
abandoned render should be cancelled, and the next line should still be answered.