Farmer Yawn

The mod plays the author's single Yawn sound:
- 2 real seconds after the player wakes up and the player sound position exists.
- At 18:30, then every 30 game minutes through 24:00.

The schedule follows in-game clock time and works at effective time scales up
to and including 240x. While the speed is above 240x, the mod skips events.
If a fast time jump crosses multiple scheduled times, the mod plays at most one
yawn in that update and skips the other crossed times.

Yawn is audio only. Sound position follows the player on foot or the current
vehicle. See SOUND_CREDITS.txt for the included user-provided recording.
