Tidy up packaging

* Save packages of different types in separate directories
* Do mot create intermediate copies of files
Update the Android port

Language and voice data files are now provided by separate packages.
The build script creates language and voice projects in
build/<host>/data/android. Before building each project, execute
"android update project -p .".
All the packages share a user id, so RHVoice can determine which
packages provide its data.
Extraction of data files is managed by a service, which accepts
requests to check or unpack data and returns the result to the caller.
The TTS service itself watches for new or updated packages and reloads
the engine (needs testing).
RHVoice now respects rate and pitch values passed by the caller.
The settings dialog has been added, though it has only one item at the
moment. There is a problem with the standard language selection dialog
provided by Android itself. I should investigate why RHVoice keeps
being called with the old value. I have probably missed something.
The most important feature which is still missing is automatic
language switching.