Main: Complete rewrite of the sequencer related audio code to support 3D Audio objects later and especially adressing the animation system problems (see mailing list if interested).
Note: Animation is not working yet, so with this commit volume animation doesn't work anymore, that's the next step.
Minor things:
* Changed AUD_Reference behaviour a little to be more usage safe.
* Fixed bug in AUD_I3DHandle: Missing virtual destructor
* Fixed enmus in AUD_Space.h
* Fixed a warning in rna_scene.c
* Removed an unneeded call in rna_sound.c