Release Name: 0.4.2

Notes:
* License changed to Artistic 2.0.
* Bug fix for Sound::ALIAS value.


Changes:
* Changed the license to Artistic 2.0.
* Updated to use the Windows::Sound module from the windows-pr library.
* Fixed the Sound::ALIAS value. It was wrongly set to SND_ALIAS_ID.
* Several gemspec updates, including the license and description.
* The Sound.get_wave_volume method is now a true alias.
* Renamed the test file to test_win32_sound.rb.
* Renamed the example file to example_win32_sound.rb to avoid any possible
  confusion with actual test files.
* Added the 'example' rake task.