Add Occlusion modes

[thedocruby]

Add Occlusion modes (Not final)

• Fast uses one occlusion pass per sound, except for some sounds like rain.
• Fair uses one occlusion pass per sound.
• Fancy uses one occlusion pass per sound, plus one on each corner for block sounds.
• Fabulous uses one occlusion pass per sound, plus one for each primary reflection bounce.