Previously, if the entity had the `can_fly` option enabled, when
going upwards or downwards, it went too fast, extremely fast, and its speed increases over time.
With this update, this no longer happens: you can customize your
own upwards and downwards maximum speed for any entity you want.
- Add LuaCheck and GitHub workflow.
- Change license to LGPLv2.1+
- Improve `README.md` and add build status badge.
- Use `mod.conf` for dependencies.
- Replace deprecated functions with newer ones.
-fixed car moving sideways caused by a shared variable,
-tweaked crash code: added enable_crash and crash_threshold variables,
-mouse steering is now default: "aux1" to toggle,
-removed is_boat in favor of terrain_type,
-tweaked mobs_redo compatablility,
-fixed speed limit enforcement
