Raffle command

!raffle is a command that users can use to enter a simple raffle.

Sub commands:

!raffle - Enter the raffle, adds username to the role.

!raffle start - Clears the role and opens the raffle.

!raffle leave - Leave the raffle, removes username from the role.

!raffle close - Closes the raffle to prevent users from entering.

!raffle open - Opens the raffle without clearing the role.

!raffle draw - Randomly draws a user from the raffle role.

!raffle clear - Clears the role.