Bugs:
+ Fixed an issue where nicknamed players or with prefixes weren't trackable.
+ Fixed an issue where you could grab player heads.

Enhancements:
+ The player will be warned in chat if the tracked player is in another dimension, and so, will be unable to track him.
+ The player will be warned in chat if he is trying to track his spawnpoint/worldspawn from another dimension, and so, will be unable to track them.