Shape SFXs in the shape_info.txt should have exclusivity

[DominusExult]

The original played only one sfx at the time (seemingly also giving priority to lower shape numbers) while we play all available sfx at the same time (with balance and distance figuring in). This leads to some sfx becoming noisy when there is a source "requesting" the same sfx especially in the case of the shape sfx (e.g. surf, water, bubbles, energy fields, orrery, generators...).

My proposal would be to limit the same sfx to playing only one at a time. Probably giving priority to the one nearest to the player.
This could be done by either

• setting this globally for the shape sfx
• adding another section to the shape sfx setting with a bool to set the sfx to exclusivity

[DominusExult]

To bring this discussion back from and including the exclusivity point in #496, if exclusivity is generally implemented it could need an exult.cfg setting to toggle this with the default enabling this. In exult.cfg maybe config/audio/effects/exclusive?