* Add menu item for reinitialising the TTS engine.
* Add settings screen for setting and changing app-specific TTS settings.
* Change the minimum required Android version to Android 5.0 Lollipop.
* Change output sound file names to use the '.wav' extension instead of '.mp4'.
* Change the app to handle input lines and text files longer than Android's maximum speech input length.
* Improve TTS initialisation and language handling.
* Make TTS notifications display process of text synthesis.
* Other bug fixes and improvements.
