AudioOutput: implementing vector clamping

- Moved positional audio related stuff to seperate functions
  setSpeakerPositions(),  positionListeren(), and locateSource()
- moved some one time calculations from calGain() to locateSource()
- Implemented vector clamping in calGain()
- For headphones the implementation falls back to the old method
- Replaced fSpeakerVolume with bSpeakerDirectional to accomodate LFE
  speakers
- Added some comments about the method
AudioOutput: Applied the feedback of dD0t
AudioOutput: Linearized the cross-over.

- Using acos(dot) insteat of 1-dot for gain calcuations
- Limited the scope of some iterator to remove shadow warnings
- Assigned float pointer to NULL pointer
improve comments,
add comments,
rm var set and used only once by using if + function call directly
declare struct AudioSourceData,
use it as return param of locateSource() and pass it to calcGain();
see pull request #35#r72812

adding some consts, commenting, more descriptive var-naming
AudioOutput: Undid some changes made by Kissaki

There was no output stream generated for 1D sound.
Update positional audio for recent mumble