* Disable stereoheadseteffects and stub out all known code references via define
By effect this also completely removes Headset sound options from the game config, as it serves no purpose whatsoever compared to stereo.
Because it's stubbed out everywhere rather than only the necessary locations to prevent it, this should boost audio runtime slightly for everything, not just the stuff that actively used it.
* Rename DISABLE_HEADSET_STEREO_EFFECTS to ENABLE_HEADSET_STEREO_EFFECTS
* Reorganize and reduce audio Note struct
* Add performance to define description
* Rename ENABLE_HEADSET_STEREO_EFFECTS to ENABLE_STEREO_HEADSET_EFFECTS