Implements the command:
/spook

• Usage: /spook <player name>

The command has two effects on the player:

• Swaps the item in the main hand of the player with a random item in his inventory
• The next time he opens a chest he gets an pumpkin equipped as helmet

Switches back to the original helmet in the following cases:

• the player clicks on the pumpkin
• the player leaves the server
• the player dies