Fixed #29 Lithium breaks stray cat behavior.

[2No2Name]

The cause of the bug is that the entity tracker is not checking whether the predicate returns true when evaluating which entity is the closest. The predicate is usually responsible for filtering out certain entities (spectators, or sometimes entities that cannot be seen using raycast, entities on the same team). Not testing the predicate leads to incorrect behavior, as for example, cats usually can't flee from spectators or creative mode players.

The fix adds checking the predicate and the given box (tracking distance of most things is only +-3 on the y axis) after the minimal distance criterion.

Of course this fix will cost some performance, but I don't see a way to get around evaluating the predicate more often than absolutely necessary without sorting the entities by distance first. Also caching the result does not seem viable, because keeping track when the cached value becomes outdated would be required.