Bug Fixes

Bugs fixed in this release

[Exploit] Zombie or skeleton horses could be ridden by visitors
[Exploit] Unrepeatable challenges could be repeated by using commands.
[Medium] Invincible visitors with (ENTITY_ATTACK prevented) were immune to PVP at spawn. They are still immune on player islands.
[Minor] API instance could be null and never change if requested before ASkyBlock was initialized.
[Minor] If admins delete a world where a warp was, then the warp location can become null.
[Minor] Fix for AAC compatibility (needs confirmation)