[gta02-core] Audio ECN update

[Rene Harder]

I just uploaded the last missing audio ECNs (ecn0036-0038), which would
need a brief discussion before implementation.

Also most audio ECN's are already implemented and need only the final
review to get closed. Especially ecn0010, ecn0015 and ecn0031-0033.

Still open is ecn0018 "Add beads/filters to audio signals
leaving/entering can" which i think can be canceled because this is
mostly taken care of in ecn0032.

Another ECN where we haven't decided yet what we are going to do is
ecn0019  "Consider applying buzz fix", so comments are welcome.


Rene