Cave Sounds

Adds cave sounds to your world
Only underground, and the interval for when cave sounds are played is decided based on the light level over time

In pitch darkness, this interval is 5 minutes

When you're near someone else when the sound plays, they'll also hear the same sound that you hear

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Credits:

cave1.ogg:
cave2.ogg:
- by Paolo D'Emilio (license: [CC BY 3.0](https://creativecommons.org/licenses/by/3.0/))
- Source: <https://opengameart.org/content/scary-monster>
- Changes: Spliced

cave4.ogg:
- by rubberduck (license: CC0)
- based on gong_01.ogg
- Source: <https://opengameart.org/content/100-cc0-sfx>

cave5.ogg:
- by Gobusto (license: [CC BY-SA 3.0](https://creativecommons.org/licenses/by-sa/3.0/))
- Source: <https://opengameart.org/content/scary-breath>
- Changes: Spliced
