When there is no TTS engine selected, mTts.getVoice() will throw
a NullPointerException. This is a workaround to cope with this bug
in Android.

This reverts commit 6ac54860a1.

This change was preventing the voice data from being installed.

The Android 5.0 Text-to-speech output settings dialog checks that
the languages from CheckVoiceData use the ISO3 language and
country codes. This change matches that expectation.

This improves the performance of looking up a voice by name.

As of Android 5.0, TextToSpeech.setLanguage calls the new
TextToSpeechService.onGetDefaultVoiceNameFor(lang,country,variant)
and uses the specified voice name.

The default Android 5.0 implementation of onGetDefaultVoiceNameFor
does not work with eSpeak. This provides a working implementation.

This fixes the TextToSpeechTest.testLanguages tests on Android 5.0.

The default Android 5.0 implementation enumerates the available
locales. This enumerates the voices returned by eSpeak.

This adds method declarations for the new voice APIs, forwarding
them to the default implementations.

The Android 4.x+ code has changed a lot since the initial import
of the eyes-free codebase. A lot of bug fixes and improvements
have been made to it.

The eyes-free codebase had two different code paths:
  *  one for ICS (4.0) or later, using the Java-based TTS APIs
     provided by the Android platform;
  *  one for pre-ICS using an internal C++-based TTS API.

Thus, any bug fixes or improvements would have to be done to both
code bases if Android 2.x/3.x support is required. This is not
maintainable.

If pre-ICS support is to be re-added in the future, the plan will
be to:
  *  forward the C++-based APIs to the Java-based APIs via a
     compatibility layer;
  *  use a compatibility layer (Android Support Library?) for using
     the ICS settings API on pre-ICS.