Audio improvements

These commits provide better separation of the various ucodes versions/revisions (we go from 3 to 19 versions !),
and implement several missing audio commands.

Most notable effects I could find include :
-PilotWings intro no more contains a ramping sound (POLEF)
-1080 Snowboarding doesn't produce garbled sound when switching from/to headset mode (RESAMPLE_ZOH)
-WaveRace doesn't produce garbled sound during race start (NEAD_16)

With respect to my "unmergeable branch", almost anything that could benefit end-user should be done now.
The remaining bits include:
- segment implementation (just for completness, because no game use it).
- mp3 ucode refactoring
- some other minor differences between revisions.