Challenge Manager

· Bug fix: When challenge complete is called, it gave every player a challenge book, without removing the previous one... · Update Challenge Book GUI for clarity: hover events, see what challenge the player is on, deny option · Add deny option to deny a player's challenge complete request: /challenge deny <player(s)> · Let player know their challenge has been denied · Let player know if they actually have been frozen/unfrozen (Before it would've let the player know nevertheless)