A new parameter `target-world` was added to set which world of a server a race takes place in. This way, tracking and notifications are limited to that world only.

This update is focused on adding more settings on how races can be run.

* Any coordinate (X, Y, Z) can be chosen instead of only X.
* Any direction (+ or -) can be chosen instead of only +.
* The leaderboard will always display the top three best scores.
* Added bStats for usage stats.

Code clean-up; no new features.