Move button creation into base Test class.
Added a sound test which plays and loops some sounds.

One of them is short, so it should call out MP3 wonkiness.
Look for a .WAV and fall back to .MP3 if it n'existe pas.
Only use BigClip for MP3, also convert anything that's not PCM.

WAV can actually contain damned near anything inside, and Java needs to be told
to covert it if you actually want to hear anything.