set_sky does work with on_joinplayer
* `"regular"`: Uses 0 textures, `bgcolor` ignored
* `"skybox"`: Uses 6 textures, `bgcolor` used
* `"plain"`: Uses 0 textures, `bgcolor` used
- * **Note**: currently does not work directly in `on_joinplayer`; use
- `minetest.after(0)` in there.
* `get_sky()`: returns bgcolor, type and a table with the textures
* `override_day_night_ratio(ratio or nil)`
* `0`...`1`: Overrides day-night ratio, controlling sunlight to a specific amount