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.

The original variant list UI resulted in a long, complex list that
was difficult to navigate. This change splits up that list into
more manageable groups.

Android does not support UN M.49 territory codes. Instead:
  *  4.2 and earlier return an empty string;
  *  4.3 throws a MissingResourceException.

This is used to filter the list of languages returned. However, the
filtering is not needed on the engine side as the client can simply
enumerate through all the available voices instead.